It's a long season; let us guide you through all of the potential names on the wire who can help your team.

Mike Aviles, Kansas City Royals -- Aviles, 29, should get a lot of at bats between second base and shortstop (he can also play third). He returned Monday after an elbow-strengthening three weeks at AAA Omaha. "My arm got better and got stronger from playing short," he told reporters. "It's good enough to make all the throws." Aviles had reconstructive elbow surgery last July 8 and hit very well in spring training. He batted .325 with 10 homers two years ago. They think he has better range than Yuniesky Betancourt at short as well. Grade B+

Starlin Castro, Chicago Cubs -- Castro, 20, is a top prospect who will play shortstop for now. Some think he still needs refinement, especially with pitch selection, base running and on defense. He's hitting .376 with one homer, 14 extra-base hits (one homer) and 20 RBIs in 26 games for AA Tennessee. He has four stolen bases but has been caught stealing five times. Ryan Theriot will move to second base. Grade B+ for the future.

Brett Cecil, Toronto Blue Jays -- Cecil, 23, is coming off three quality starts for the injured Brian Tallet. He is a sinker-slider pitcher with an improving changeup and is a decent prospect for this year. He had seven wins and a 5.30 ERA in 18 games (17 starts) for the Jays last year. He was a first round pick in 2007. Grade B-

Manny Corpas, Colorado Rockies -- Corpas, 27, seems to have passed Franklin Morales as the Rockies closer until Huston Street returns in 3-4 weeks. Corpas has been used twice in the past four games. Morales won the closer's job in spring training but has been wild. On the other hand, Corpas has a 1.66 ERA. Elbow surgery ruined his season last year. Grade B

Omar Infante, Atlanta Braves -- Infante, 28, will play shortstop position with Yunel Escobar on the disabled list. Infante, a utility player, is strongest on defense at shortstop and second base but he can also play third and all three outfield positions. He batted .293 and .305 with five homers and two steals the last two years for the Barves. Grade C+

Kila Ka'aihue, Kansas City -- Don't pick him up yet, but if Jose Guillen, who is in the final year of his contract, gets traded in the next couple of months, he could pick up extra playing time at DH. Ka'aihue, 26, is a first baseman by trade but is not a very good defensive player so DH might be his ultimate destination. But he can hit (.304 with seven homers at AAA Omaha) and draws loads of walks. Grade C+

Kris Medlen, Atlanta Braves -- Medlen, 24, could get a few starts for the injured Jair Jurrjens (although they are hoping he just misses a start or two). The 24-year-old right-hander posted a 3.95 ERA and 1.55 WHIP over his first 48 major league appearances (four starts), averaging just over a strikeout per inning. He made four spot starts last year. Grade C+

Scott Olsen, Washington Nationals -- Olsen, 26, has thrown straight quality starts under his belt and says he is finally healthy. He had season-ending surgery to repair a torn left labrum last July. He has decent stuff with improved velocity, low-to-mid 90s fastball, with a slider and changeup, but needs to continue his overall consistency. Looks good for now. Grade B

Koji Uehara, Baltimore Orioles -- Uehara, 35, was just activated and provides Dave Trembley with some important insurance behind closer Alfredo Simon. He was a starter last year but was switched to the bullpen as he struggles the second time through a lineup. He was a starting pitcher almost exclusively in Japan until 2007 when he became a closer and saved 32 games. Grade B

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