Alberto Callaspo, 2B, Arizona Diamondbacks. Callaspo has already had some short stints in the majors this season, so he is sure to see time in September. Acquired from the Angels in spring training, Callaspo is almost a sure thing as a regular in the majors. He is excellent defensively, has hit well above .300 in Triple-A this season and has incredible plate discipline. Although his power and speed are only average, they are hardly any worse than current Arizona second baseman Orlando Hudson. The Diamondbacks could look to move Hudson this offseason as a direct result of Callaspo, and he has the ability to help NL-only owners in average during September if given playing time.
Rajai Davis, OF, Pittsburgh Pirates. Does anyone actually think the Pirates know what they are doing with their current outfield situation? Of course Jason Bay is a fixture, but otherwise, the regulars for next season are anyone's guess. Enter Davis. He is a prototypical leadoff hitter, which means he has the ability to help owners with steals. He has decent contact ability and was hitting .283 with 45 steals at Triple-A Indianapolis this season. Davis could see time in September as the Pirates try to decide who deserves their two open outfield spots among Davis, Jose Bautista, Nate McLouth and Chris Duffy.
Andrew Miller, P, Detroit Tigers. Miller was widely considered the best player available in June's amateur draft, but his monetary demands dropped him to the sixth overall pick. This lanky southpaw has pitched well thus far and is guaranteed a September call in his contract. Although Miller has almost no chance of finding starts in September, he could provide quality innings in a long relief role. Plus, he could compete for a rotation spot as soon as next spring.
Hayden Penn, SP, Baltimore Orioles. Penn would have been pitching in the majors much earlier this season if not for an emergency appendectomy shortly after his promotion to Baltimore. His control was not ready for the jump from Double-A to the majors last season, but he has made major progress this year and continues to post about a strikeout per inning. His success relative to age at each level also shows that Penn, 21, could become an eventual ace. He should get a rotation spot in September and go on to help fantasy owners from there.