A player's stat line from the previous season often determines his fantasy value -- but that's often where many owners make a mistake. Drafting based off of last year's statistics would give an owner the best team for the previous season, filled with players coming off of career years, but not the best team for the season ahead.
To help our readers avoid that problem, we present SI.com's annual series on finding the breakthrough players before they actually break through, and we start with this writer's favorite category of all: 27-year-old breakout candidates.
A baseball player's prime is widely considered to come from age 26-32, but history shows that something special seems to happen at age 27. That's when a player typically hits his physical peak, and often, drafting 27-year-olds can help fantasy owners score players who outperform their fantasy draft position.
Take last season: David Price, Matt Cain, Gio Gonzalez, Adam Jones, Max Scherzer and Jarrod Saltalamacchia -- all 27 years old -- were their best yet. It also happens in football: Just look at Adrian Peterson's monster rushing season, or Calvin Johnson's record-breaking receiving season from last fall. They're all proof of how magical the age can be for an athlete.
Our age-27 theory focuses on picking players who are perhaps under-drafted and primed to put their best season together. We break our top picks into two categories: 1) Those who could wind up as fantasy MVPs and 2) those who are potential sleepers.
Five 27-year-old fantasy MVPs
? Birthdate: Oct. 7, 1985 ? Career bests: .294 AVG, 33 HR, 113 RBI, 100 R, 15 SB, .372 OBP, .531 SLUG ? Upside: .310/35/120/110/10/.400/.600
We're all well aware of what Longoria is capable of, but he's still carrying the stigma of injuries. However, there's no way that Longoria's best years are behind him; only now entering his prime years of production, one of the stars of the game is about to legitimately rise to the top. This third-round pick in mixed leagues could become a top-three player overall at age 27.
? Birthdate: April 8, 1986 ? Career bests: .252/27/79/84/5/.365/.457 ? Upside: .275/30/100/90/5/.400/.525
Santana has been drafted as an elite catcher for years, and he'll likely go in the top five at the position, but he has the potential to be the most productive catcher in fantasy. His strong walk rate besets his poor career batting average (.247), and the Indians often keep the DH spot open for him on the days he is not behind the plate. He is going to go many rounds after Buster Posey, but Santana is a better value relative to draft position. This might be the big year for Santana for which so many have waited.
? Birthdate: Aug. 11, 1986 ? Career bests: .330/25/90/79/5/.387/.556 ? Upside: .330/30/100/90/5/.400/.580
Kung Fu Panda is coming off a World Series MVP showing, but fantasy owners are still weary of the injury-prone stigma attached to him. He battles weight issues, but that allows him to slip in drafts. He also tends to be an every-other-year player statistically, and this is the odd year in which he should hit better than .300 with a .550-plus slugging percentage. This is the perfect time for him to put together a complete season.
? Birthdate: May 23, 1986 ? Career bests: 12 W, 2.94 ERA, 1.150 WHIP, 153 Ks in 195 2/3 innings ? Upside: 20/2.45/1.050/180 in 220 innings
Zimmermann is already coming off a career year, but he is lost a bit behind the likes of Stephen Strasburg, 27-year-old breakthrough Gio Gonzalez and even the offseason acquisition of former fantasy ace Dan Haren. Pitching for arguably the best team in baseball, Zimmermann has shown he can be as good as anyone, and will be a good value at his draft position, particularly since his career-high in victories is just 12. We wouldn't be surprised to see him finish second to Strasburg in the NL Cy Young race and a 20-game winner at age 27.
? Birthdate: May 21, 1986 ? Career bests: .262/23/83/72/3/.329/.450 ? Upside: .290/30/100/85/5/.375/.500
Wieters is already coming off a career year at age 26, but even more is possible. Like the Indians with Santana, the Orioles figure to keep the burgeoning backstop star in the lineup as a DH when he needs time off from behind the plate. Also, there is plenty of room to grow in the ratio categories of average, on-base percentage and slugging. The three consecutive years of growth and statistical improvement won't stop at age 27 -- this will be another career year.
Five 27-year-old fantasy sleepers
? Birthdate: Sept. 16, 1986 ? Career bests: .270/16/63/62/7/.347/.460 ? Upside: .285/25/90/90/15/.365/.500
Beckham is our favorite late-round 27-year-old breakout in this year's class. He arrived with incredible hype as an early first-rounder out of Georgia and posted Dustin Pedroia-like numbers for two-thirds of 2009. It has been a struggle since; in fact, he has been consistently low end to mediocre in fantasy. Remember, it took Chase Utley until Beckham's current age to become a fantasy superstar, and Utley has been the gold standard for a run-producing fantasy second baseman since.
? Birthdate: Jan. 5, 1986 ? Career bests: .233/23/78/47/1/.288/.438 ? Upside: .260/30/90/60/1/.320/.480
We are a bit uneasy about having a third catcher on this list, particularly on the grounds that we expect dramatic improvement in the batting average. Catchers tend to be drags in the category. Arencibia is coming off a year where he took a step back, but that bolstered Blue Jays lineup can ignite him at age 27. He will be a great source of power at arguably the thinnest position in fantasy. He's a steal at his draft position -- because of his career .222 average -- something than can be said for very few catchers.
? Birthdate: March 17, 1986 ? Career bests: .270/33/85/75/3/.326/.501 ? Upside: .275/35/100/85/3/.333/.525
Davis turns 27 on St. Patrick's Day. It's easy to forget Davis is just now entering his prime. He has wallowed around in fantasy mediocrity for years -- until last season. The years of disappointment might make some think his 2012 totals of 33 homers and 85 RBI are a bit of a fluke. Nope. That was a coming of age. Davis is well worth his draft position and can grow into one of the game's feared sluggers.
? Birthdate: Nov. 26, 1985 ? Career bests: .294/6/46/44/1/.365/.463 ? Upside: .300/15/90/90/10/.400/.475
It isn't the offensive production he provides as a corner infielder that excites anyone. It is his potential transition to second base, where he can start for the Cardinals. Reports have him doing well there and it is possible he gets 500 at-bats for the first time. His bat is plenty good enough to slot as a starter at the thin position in all fantasy leagues when he becomes eligible there.
? Birthdate: Aug. 6, 1986 ? Career bests: 5 W, 1.95 ERA, 0.800 WHIP, 73 Ks, 0 SV ? Upside: 5/1.50/0.750/80/30 SV
The 27-year-old axiom doesn't necessary apply to pitchers, especially relievers, but McGee has taken years to reach his full potential as a late-inning option for the Rays. He arrived as one of the best setup men in baseball and the next logical step is to close. With Fernando Rodney coming off a career year impossible to duplicate -- particularly when you consider Rodney's year-to-year inconsistency throughout his career -- we could see McGee morph into a top-five closer in fantasy if he inherits the role. He's worth a starting spot in rotisserie formats for that potential scenario alone, and even if he doesn't get that promotion, he'll still be a great middle reliever at age 27.
Top 27-year-olds by position
The potential 27-year-old breakthroughs won't end there. Here's a list of our favorites, ranked by position: