This is Baseball America's 21st annual Top 100 Prospects list, our definitive annual ranking of the best professional talent in baseball below the major league level. And this year we're turning the focus of the list to the best tool for each player. We'll highlight that tool, as well as giving it a grade on the 20-80 scouting scale -- where 20 is the worst, 80 the best and 50 major league average.

The Top 100 Prospects list is the culmination of BA's offseason prospect coverage, which begins with reviews of the top talent in each minor league and proceeds with ranking the talent in each major league farm system. Our staffers and correspondents talk to general managers, managers, scouting directors, farm directors, scouts, coaches and other baseball insiders. Four BA staffers contributed to the voting this year: Co-editors Will Lingo and John Manuel, executive editor Jim Callis and assistant editor Conor Glassey. Each compiled a top 150 list, and we then reviewed the composite numbers and made adjustments before locking down the final list.

The rankings follow BA's standard prospect guidelines, which means that any player who has not exceeded 130 at-bats, 50 innings or 30 pitching appearances in the major leagues (without regard to service time) is eligible. As always, our appraisal is not necessarily based on what a player will do this season, but what his ultimate major league ceiling is, weighed against the likelihood that he will reach that ceiling.

The Rays had the most prospects on the list, with seven. For a complete breakdown of the list, go here.

RELATED CONTENT: How have previous Top 100 prospects fared in their careers?

Age: 20 Major League ETA: 2010 Best Tool: Bat BA Grade: 80

The best combination of hitting ability, power and athleticism in the minors; scouts believe that this 20-year-old has a chance to hit .300 with 30 home runs or more.

Age: 21 Major League ETA: Mid-2010 Best Tool: Fastball BA Grade: 80

Strasburg has a premium breaking ball, and his fastball is the minors' best in terms of velocity, command and liveliness.

Age: 20 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 80

Another prototypical right fielder like Heyward; Stanton is stronger and perhaps more athletic, but lacks Heyward's pure hitting ability.

Age: 20 Major League ETA: 2011 Best Tool: Power BA Grade: 80

Montero isn't a pure hitter, but he's as good offensively as any prospect; he's unlikely to catch everyday and already has taken grounders at first base this spring.

Age: 23 Major League ETA: 2010 Best Tool: Changeup BA Grade: 70

The most big-league-ready pitcher on the list. Matusz's changeup, slider and curveball all rate above-average, as does his fastball command.

Age: 23 Major League ETA: Mid-2010 Best Tool: Speed BA Grade: 80

Another athletic, well-rounded Rays outfielder, but Jennings isn't raw, especially in terms of his polished offensive approach.

Age: 23 Major League ETA: Mid-2010 Best Tool: Bat BA Grade: 70

The best hitter the Giants have drafted since Matt Williams. Posey's defense (specifically handling velocity) is the last major improvement he needs to make.

Age: 23 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 80

The Pirates have plenty of needs, and Alvarez won't solve all their problems, but the streaky slugger could be a 40-homer threat by 2011.

Age: 21 Major League ETA: 2010 Best Tool: Fastball BA Grade: 80

The Rangers' power pitcher has developed a devastating changeup to go with his premium fastball.

Age: 23 Major League ETA: 2010 Best Tool: Power BA Grade: 65

Switch-hitter with patience and power who should be ready by the second half of 2010 to handle daily duties behind the dish.

Age: 22 Major League ETA: 2011 Best Tool: Bat BA Grade: 80

The best pure hitter to come out of college baseball since Robin Ventura in the late 1980s should have multiple batting championships in his future, no matter what position he plays.

Age: 23 Major League ETA: 2010 Best Tool: Defense BA Grade: 70

He's more ready to make take over as an everyday SS than Elvis Andrus was at the same time last year. His ceiling is lower, but his first season or two should be better.

Age: 23 Major League ETA: Mid-2010 Best Tool: Bat BA Grade: 70

Ten teams passed on Smoak in the 2008 draft, yet he should be ready to seize a starting job in Texas this year, providing defense and power from both sides of the plate.

Age: 20 Major League ETA: Mid-2010 Best Tool: Fastball BA Grade: 65

Scout like the way he commands and uses his fastball; his numbers in the minors (27-5, 1.65, 55 BB/256 SO in 273 IP) speak for themselves.

Age: 22 Major League ETA: 2011 Best Tool: Arm BA Grade: 70

He's not ready defensively, and the Phillies have Raul Ibanez and Jayson Werth set for 2010. But Brown's lanky, athletic body and hitting tools could make him Philly's next star.

Age: 20 Major League ETA: 2011 Best Tool: Bat BA Grade: 65

Castro burst on the scene in 2009, jumping from Rookie ball to Double- A in a year. He has intriguing power potential and defensive chops for the middle infield.

Age: 19 Major League ETA: Mid-2011 Best Tool: Curveball BA Grade: 65

Still a teenager, Perez has scouts dreaming on his three out-pitches: fastball, curve and changeup.

Age: 22 Major League ETA: Mid-2010 Best Tool: Command BA Grade: 65

"Hellboy" is the latest Rays pitching product, and while he's also the smallest, his fastball command, changeup and curve should help him fit in in Tampa.

Age: 20 Major League ETA: Mid-2011 Best Tool: Arm BA Grade: 75

A scratch golfer as a teen, Hicks is just learning to translate his prodigious tools -- which include tremendous arm strength, speed and power potential --into skills.

Age: 22 Major League ETA: 2010. Best Tool: Bat BA Grade: 65

An alum of Albert Pujols' junior college, Morrison has the hitting ability to seize Florida's first-base job as soon as he's ready.

Age: 19 Major League ETA: 2012 Best Tool: Speed BA Grade: 70

In just 60 games as a pro, Westmoreland has shown the tools and flashes of the skills to be a trade-deadline chip for years to come.

Age: 22 Major League ETA: Mid-2010 Best Tool: Fastball BA Grade: 80

The Reds are betting $30 million that this latest Cuban import -- with the 100 mph fastball -- will live up to at least some of the hype.

Age: 19 Major League ETA: 2012 Best Tool: Fastball BA Grade: 65

Matzek uses an old-school delivery but delivers 21st-century heat with a fastball that at times reaches 98 mph.

Age: 20 Major League ETA: Mid-2011 Best Tool: Command BA Grade: 70

After trying to play shortstop and pitch last year, Kelly has focused his premium athletic ability (he turned down a football scholarship to play quarterback at Tennessee) exclusively on the mound.

Age: 22 Major League ETA: Mid-2010 Best Tool: Curveball BA Grade: 70

Having had to live up to his big league name, now Drabek has to live up to being the main cog in the Roy Halladay trade.

RELATED CONTENT: Now or never for former top prospects

Age: 18 Major League ETA: 2012 Best Tool: Fastball BA Grade: 70

A Missouri prep product, Turner's prep catcher was Mike Matheny's son, and Todd Worrell was his high school pitching coach.

Age: 23 Major League ETA: Mid-2010 Best Tool: Bat BA Grade: 70

Already on to his third organization, the 2008 first-round pick has proved that he can hit, and that he's better suited for first base than third.

Age: 23 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 75

Oakland's utter lack of big league power screams out for Carter, a key piece from Arizona in the Dan Haren trade.

Age: 24 Major League ETA: Mid-2010 Best Tool: Bat BA Grade: 65

The Stanford alum returns to the Bay Area after being traded straight-up for Wallace; his all-around game and right-handed bat should force him into Oakland's woeful lineup.

Age: 23 Major League ETA: 2010 Best Tool: Power BA Grade: 60

Another alum of the Mariners' international house of prospects, this Canadian has no true weakness and should wind up an above-average offensive player.

Age: 21 Major League ETA: Mid-2011 Best Tool: Bat BA Grade: 60 The Indians are in full rebuilding mode, and Chisenhall -- a smooth left-handed hitter with power and athletic ability -- should be a cornerstone.

Age: 20 Major League ETA: 2011 Best Tool: Bat BA Grade: 60

He's barely shaving, yet Freeman already provides a powerful wingman for Jason Heyward and should follow him to Atlanta next year.

Age: 22 Major League ETA: 2011 Best Tool: Curveball BA Grade: 60

The Rockies have developed their own arms of late, and Friedrich should bring two plus breaking balls and a knack for the strike zone to Coors Field soon.

Age: 24 Major League ETA: 2010 Best Tool: Fastball BA Grade: 65

The Rays have taken their time with this 2004 draft pick, and Davis is ready to reward them with an excellent fastball, a plus curve and a solid four-pitch mix.

Age: 20 Major League ETA: 2012 Best Tool: Fastball BA Grade: 65

Another Rays pitching prospect, the third member of the top 35. He has held minor leaguers to a .180 average through 198 career innings.

Age: 21 Major League ETA: 2012 Best Tool: Slider BA Grade: 70

Parker will miss 2010 due to ligament replacement surgery in his throwing elbow. When healthy, his fastball and slider earned 70 grades from scouts.

Age: 23 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 60

Baltimore bought the power-hitting Bell time with veteran offseason acquisitions, giving him time to work on his defense and right-handed swing.

Age: 21 Major League ETA: 2012 Best Tool: Power BA Grade: 60

One of the minors' best offensive season in 2009 came from Norris, who must show the effort defensively needed to remain a full-time catcher.

Age: 20 Major League ETA: Mid-2011 Best Tool: Fastball Major League ETA: 60

The Royals haven't had much player-development success of late to go with Zack Greinke. Can they harness this powerful left-handed arm?

Age: 23 Major League ETA: 2011 Best Tool: Fastball BA Grade: 65

How about back-to-back Royals? This former Missouri ace is likely to reach the majors quicker than Montgomery, and could become Greinke's wingman.

Age: 22 Major League ETA: Mid-2010 Best Tool: Bat BA Grade: 60

Castro the Astro doesn't have the same upside as some of those ranked behind him, but he's a good bet to hit his way to the big leagues and defend at an average level.

Age: 23 Major League ETA: 2011 Best Tool: Fastball BA Grade: 70

Scheppers' stuff has explosiveness, with a fastball that approaches 100 mph and a big-time curveball. His past shoulder woes, though, are part of every conversation.

Age: 24 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 60

The Reds haven't picked a position for this former Little League World Series hero from Toms River, N.J. His best one is probably batter's box anyway.

Age: 24 Major League ETA: 2011 Best Tool: Fastball BA Grade: 70

The key to Boston's acquisition of catcher Victor Martinez last July, Hagadone was Tim Lincecum's closer at Washington, and as a starter now, he has three plus pitches at times.

Age: 22 Major League ETA: 2011 Best Tool: Bat BA Grade: 65

A bad-bodied pure hitter, Alonso might be ready before the Reds have decided what to do between him and incumbent Joey Votto.

Age: 21 Major League ETA: 2012 Best Tool: Speed BA Grade: 80

Perhaps the minors' fastest actual prospect, Gordon has a lithe, athletic body that doesn't evoke his big league dad, Tom (Flash) Gordon.

Age: 21 Major League ETA: Mid-2011 Best Tool: Fastball BA Grade: 70

Another athletic pitcher, Crosby has well above-average velocity for a left-hander and is a prime candidate for a breakout 2010 season.

Age: 21 Major League ETA: Mid-2011 Best Tool: Fastball BA Grade: 70

Another breakout candidate with big stuff, Withrow missed parts of two seasons with injuries but reached Double-A in his first healthy campaign last year.

Age: 19 Major League ETA: 2012 Best Tool: Fastball BA Grade: 60

The Giants' next wave of prospects after Bumgarner and Posey starts with Wheeler, a live-armed Georgia prep product in the Adam Wainwright tradition.

Age: 19 Major League ETA: 2012 Best Tool: Fastball BA Grade: 65

A Texas flamethrower, Miller has reached 97 mph with his fastball and stands out in an otherwise thin Cardinals farm system.

Age: 19 Major League ETA: Mid-2012 Best Tool: Fastball BA Grade: 65

Scouts have buzzed about this Colombian's live arm since the Braves signed him for $850,000 in 2007.

Age: 22 Major League ETA: Mid-2011 Best Tool: Bat BA Grade: 60

Scouts are mixed on how high Green's upside might be, but they agree that he's an athletic middle infielder.

Age: 19 Major League ETA: 2012 Best Tool: Speed BA Grade: 70

A North Carolina football recruit, Tate gave up the gridiron for a $6 million signing bonus. He's by far the Padres' best athlete, but it might take his bat a while to catch up.

Age: 24 Major League ETA: 2010 Best Tool: Defense BA Grade: 60

It's hard to find left-handed-hitting shortstops, and it's even harder to find those who can handle the position, deliver gap power and do it at Triple-A like Brignac has for two seasons.

Age: 21 Major League ETA: Mid-2011 Best Tool: Speed BA Grade: 70

Mitchell won national championships in football and baseball at Louisiana State; he has significant upside in baseball once he taps into his raw power potential.

Age: 20 Major League ETA: 2011 Best Tool: Fastball BA Grade: 70

Mejia has above-average stuff and has had some Double-A success, but he has to show the durability and control to be a starter.

Age: 21 Major League ETA: Mid-2011 Best Tool: Fastball BA Grade: 65

Don't sleep on this Padres farmhand, who generates mid-90s velocity with ease and has the body to become an innings-eating, mid-rotation starter.

Age: 22 Major League ETA: 2011 Best Tool: Arm BA Grade: 70

As long as Joe Mauer is in town, Minnesota doesn't exactly have a pressing need behind the plate, which makes Ramos -- a Venezuelan with plus raw power, good size and a cannon arm -- excellent trade bait.

Age: 20 Major League ETA: Mid-2011 Best Tool: Power BA Grade: 65

The highest-drafted Canadian hitter ever has the athleticism to stay in the infield and enough offensive potential to make an impact if he moves to the outfield.

Age: 24 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 65

Acquired from Atlanta in the 2008 Javier Vazquez trade, Flowers has improved defensively but has enough of a bat to succeed even if he gives up the tools of ignorance.

Age: 22 Major League ETA: 2011 Best Tool: Slider BA Grade: 65

The latest in Missouri's pitching assembly line, Gibson has an excellent slider that he complements with a plus-changeup and command of a good sinking fastball.

Age: 23 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 65

The son of ex-big league reliever Ron Davis focuses on hitting for power as a pro and helped lead Team USA to the World Cup gold medal last September.

Age: 22 Major League ETA: Mid-2011 Best Tool: Sinker BA Grade: 65

Britton had a breakout year in 2009, ranking among minor league leaders in groundball outs thanks to his lethal low-90s sinker, the best in the minors.

Age: 19 Major League ETA: 2012 Best Tool: Fastball BA Grade: 70

Knapp was the most talented minor leaguer the Phillies sent to Cleveland in the Cliff Lee trade, but he has also already had shoulder surgery. When he's right, he has shown three plus pitches.

Age: 21 Major League ETA: Mid-2011 Best Tool: Splitter BA Grade: 65

White's athleticism and competitiveness made him an ace in college at North Carolina. The development of his slider will determine whether or not he makes it as a starter or has to close as a pro.

Age: 23 Major League ETA: 2010 Best Tool: Command BA Grade: 65

Hudson zoomed from A-ball to the big leagues in one professional season and can factor into the White Sox staff in 2010 either as a starter or a reliever.

Age: 20 Major League ETA: 2012 Best Tool: Power BA Grade: 60

The No. 1 overall pick in 2008 didn't take pro ball by storm in 2009 but didn't disappoint, either. Beckham has the potential to hit for plus power on the left side of the infield.

Age: 21 Major League ETA: Mid-2012 Best Tool: Fastball BA Grade: 70

The Rays have no need to rush their minor league pitchers, but Colome gives them yet another big arm to develop or use as a trade chip down the line.

Age: 19 Major League ETA: Mid-2012 Best Tool: Curveball BA Grade: 70

The key to the Javier Vazquez deal from Atlanta's standpoint was the live-armed Vizcaino, who has a fastball that reaches the mid-90s to go with an excellent curveball.

Age: 20 Major League ETA: 2012 Best Tool: Power BA Grade: 65

While his approach is a bit too aggressive, Vitters hit for impressive power in 2009. He has time to grow into his role as Aramis Ramirez's eventual replacement.

Age: 22 Major League ETA: Mid-2010 Best Tool: Changeup BA Grade: 60

The Rockies system has impressive pitching depth, including the four-pitch mix of Chacin, who thrives when he pitches off his hard sinker -- tailor-made for Coors Field.

Age: 22 Major League ETA: 2011 Best Tool: Command BA Grade: 70

Leake has evoked Tim Hudson comparisons for a couple of years for his ability to manipulate the baseball; his only question mark is holding up after a heavy college workload (340-plus innings in three seasons).

Age: 19 Major League ETA: 2012 Best Tool: Defense BA Grade: 60

The thin Astros farm system got a boost when Mier (on the thin side himself) exceeded expectations offensively in his debut; scouts consider him a good bet to stay at shortstop, too.

Age: 21 Major League ETA: Mid-2011 Best Tool: Power BA Grade: 65

After a down spring at California, Jackson had an excellent debut and could solve the Cubs' center-field hole in the near future, perhaps as soon as next season.

Age: 23 Major League ETA: Mid-2010 Best Tool: Arm BA Grade: 70

Reddick has tools to spare and is close to being ready for an everyday spot; polishing his offensive approach is the last piece of the puzzle.

Age: 23 Major League ETA: 2010 Best Tool: Bat BA Grade: 60

The former Georgia Tech point-guard recruit has had success in the high minors and should be ready to play center field in Detroit after coming over in the Curtis Granderson deal.

Age: 21 Major League ETA: Mid-2010 Best Tool: Power BA Grade: 60

It seems like he has been around forever, but he's still just 21. Martinez's bat keeps showing improvement, leading him to MVP honors in the Caribbean Series.

Age: 19 Major League ETA: 2012 Best Tool: Fastball BA Grade: 60

The Marlins love Oklahoma when it comes to draft time (see Josh Johnson), and they popped the live-armed southpaw James in the first round last year.

Age: 21 Major League ETA: Mid-2011 Best Tool: Defense BA Grade: 70

Considered a bit of a reach when drafted fourth overall last year, Sanchez has quickly shown that he belongs, with big league-caliber defense.

Age: 21 Major League ETA: Mid-2011 Best Tool: Power BA Grade: 70

California's all-time prep home run king has to be more selective, but should provide the Royals with power at a corner spot, either at third or in the outfield.

Age: 21 Major League ETA: 2012 Best Tool: Power BA Grade: 60

After a horrible start to 2009, d'Arnaud recovered to hit low-Class-A Lakewood to the South Atlantic League title and became a key piece in the Roy Halladay trade.

Age: 20 Major League ETA: Mid-2011 Best Tool: Bat BA Grade: 65

He might be the worst athlete on the list, but Decker's hitting ability, patience and power evoke comparisons to Matt Stairs and John Kruk.

Age: 25 Major League ETA: 2010 Best Tool: Arm BA Grade: 60

Kenji Johjima's return to Japan has opened a spot behind the plate in Seattle. Moore's solid tools and fairly accomplished bat should allow him to seize the starting job.

Age: 22 Major League ETA: 2011 Best Tool: Power BA Grade: 60

Conger's defense could use some polishing, but when he has been healthy he has shown switch-hitting power at a premium defensive position.

Age: 18 Major League ETA: Mid-2012 Best Tool: Speed BA Grade: 75

From the Jersey shore to the Angels' first-round pick, Trout makes scouts think of Aaron Rowand with his all-out style; he also has top-of-the-line speed.

Age: 21 Major League ETA: Mid-2011 Best Tool: Arm BA Grade: 60

Jesus Montero is the better prospect, but Romine is the better defender and more likely to succeed Jorge Posada in New York. He's the son of ex-big leaguer Kevin Romine.

Age: 22 Major League ETA: Mid-2011 Best Tool: Power BA Grade: 60

Anderson's star dimmed in 2009, but he still has a smooth, left-handed swing and power potential. His Double-A struggles may indicate that he's more of a solid regular than a star.

Age: 18 Major League ETA: Mid-2012 Best Tool: Power BA Grade: 60

Flores won't be a shortstop long-term, and scouts are mixed on whether he can stay in the infield. They agree that he can hit and should show big power down the line.

Age: 24 Major League ETA: 2010 Best Tool: Bat BA Grade: 60

He's not technically a rookie because of service time, but Gamel has yet to establish himself in Milwaukee. Look for that to happen this year thanks to his line-drive bat.

Age: 23 Major League ETA: Mid-2011 Best Tool: Power BA Grade: 60

Darnell's mix of raw power and athletic ability has evoked comparisons to Ryan Braun, but he doesn't quite have that kind of upside.

Age: 19 Major League ETA: 2012 Best Tool: Command BA Grade: 60

The best pitcher in a thin Astros organization, Lyles has shown three average pitches with the potential for more, and he fills up the bottom of the strike zone.

Age: 22 Major League ETA: Mid-2010 Best Tool: Slider BA Grade: 65

After helping Stanford reach the College World Series in 2008 as a freshman closer, Storen pitched his way into the first round in 2009 and has a premium slider to go with a good fastball.

Age: 21 Major League ETA: Mid-2011 Best Tool: Sinker BA Grade: 65

Aumont earned comparisons to Kevin Brown as a Canadian amateur and will return to a starting role with the Phillies after coming over in the Cliff Lee deal.

Age: 16 Major League ETA: 2013 Best Tool: Arm BA Grade: 70

The biggest catch in the international talent pool last year was made by Minnesota, which loves Sano's power bat, size and throwing arm.

Age: 23 Major League ETA: Mid-2010 Best Tool: Fastball BA Grade: 75

Cashner has flashed near-100 mph heat and a plus breaking ball in shorter stints and looks like a reliever long-term. He gave up only one homer in 2009.

Age: 22 Major League ETA: Mid-2011 Best Tool: Bat BA Grade: 60

While he's just a fair athlete, Neal stands out -- particularly with the Giants -- for having a polished offensive game with patience and power.

Age: 23 Major League ETA: 2011 Best Tool: Speed BA Grade: 70

The son of a scout, Bourjos has premium speed and defensive tools in center field, and while he has raw power, he employs a small-ball approach that should endear him to Mike Scioscia.

Age: 22 Major League ETA: 2011 Best Tool: Fastball BA Grade: 60

The Cubs found this Furman product in the ninth round and he finished last season in Triple-A. If Jeff Samardzija struggles in the rotation, watch for Jackson as soon as this year.

Age: 24 Major League ETA: Mid-2010 Best Tool: Fastball BA Grade: 60

There's hope in Baltimore thanks to a bevy of young pitchers such as Arrieta, who has a live fastball that at times sits in the mid-90s.

Age: 20 Major League ETA: 2012 Best Tool: Fastball BA Grade: 60

Another Cuban defector highly regarded for his live arm and athletic ability, having earned comparisons to a pre-Tommy John surgery Francisco Liriano.

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