Fantasy source. (TSNumber 17).

Mark Prior has amazing stuff: a mid-90s fastball and baffling off-speed arsenal. It won't be long before his performances force the Cubs to give him a chance in the majors. In his first five starts at Class AA this year--his first experience as a pro--Prior, 22, was 4-1 with a 2.22 ERA. In 28 1/3 innings, he gave up 19 hits and eight walks and struck out 48. And he's hardly the only player who might have a big impact if he were called up.

Ryan Bukvich, RP, Royals: If Roberto Hernandez (elbow) can't stay healthy, Kansas City desperately will need a closer. In his first 15 innings at Class AA, Bukvich allowed one unearned run, four hits and four walks. Bukvich, who turns 24 Monday, throws in the mid-90s and had six saves and 23 strikeouts.

Carl Crawford, CF, Devil Rays: Crawford, 20, has been terrorizing Class AAA pitching, hitting .333 with 20 runs, 14 RBIs, a .636 slugging percentage and six steals in his first 26 games. His plate discipline needs work but should improve with experience. It might not be long before Crawford is producing a .300 average, 15 to 20 homers and 40 steals in the majors.

Jack Cust, OF, Rockies: The team's outfield is filled now, but he could be a monster if he gets a chance to play full-time. Cust, 23, had 16 extra-base hits (nine homers) and 19 RBIs in his first 83 at-bats at Class AAA this year. Though he piles up the strikeouts, he walks a ton and has a nice on-base average.

Bobby Hill, 2B, Cubs: Hill, 24, has the skills to be an excellent leadoff hitter--and a huge improvement over Delino DeShields. Hill was slowed by a virus early this season and hit .197 in his first 21 games at Class AAA. Still, he had a nice walk rate and was perfect in six steal attempts.

Josh Phelps, C, Blue Jays: His walk rate is way down, but Phelps, who turns 24 on Sunday, has the power and defense to take over in Toronto by June. Darrin Fletcher is the team's starter but probably not for long. Toronto is in a rebuilding mode and must be itching to see what Phelps can do on the big club.

Brandon Phillips, SS, Expos: He almost was unstoppable at Class AA in April, hitting .386 with six homers and 17 RBIs. With 10 walks in his first 21 games, he has improved his plate discipline dramatically. He had just 12 walks in 67 games last year. Phillips, 20, could play ...