Prior to the rosters expanding in September, there was speculation that the Arizona Diamondbacks would call up their first-round draft pick Trevor Bauer to boost their bullpen for the stretch. They never called up Bauer, who has struggled in his brief trial at AA, but on Monday they called up their top prospect entering the season, Jarrod Parker.

Parker was the seventh pick in the 2007 draft, and the first high-school pitcher taken, selected before Rick Porcello and Madison Bumgarner. Parker was projected to be a fast riser through the system, and he started his pro career strong:

But if you're wondering what the void between '09 and '11 is, that's the Tommy John gap. Parker blew out his elbow in 2009, requiring ligament replacement. John Sickels suggests that he's using fewer sliders since coming back:

His key pitch is a hard sinking fastball, working at 92-95 and hitting 96-97 at its best. He's lost no velocity since the surgery, although he's still working on command refinements.

His slider was his out-pitch pre-surgery. Scouting reports indicate that he's not throwing it as much as he used to, but it still rates as a plus pitch. His changeup has improved a great deal, ranking plus at its best, and he'll mix in some curves on occasion, giving him four pitches to work with. He's especially tough on right-handed hitters, holding them to a .209 average with just two homers this year.

Though the Diamondbacks technically haven't clinched yet, the call-up of Parker is likely a move made with an eye on the future rather than on the current pennant race -- he's more likely to pitch some low-leverage innings than get thrown into the rotation or late-inning bullpen mix. If he impresses, though, his fastball could get him on the postseason roster if the Diamondbacks want to use the Francisco Rodriguez loophole.