The Diamondbacks today dipped into their enviable stash of pitching depth at Double-A Mobile, though they didn't call up No. 1 prospect Trevor Bauer or top lefty Tyler Skaggs. Instead they added 22-year-old southpaw Pat Corbin to the 40-man roster so that he can take Josh Collmenter's place in the big league rotation. He will oppose the Marlins and Mark Buehrle today.

An athletic lefthander who throws strikes with average stuff, Corbin impressed Arizona decision-makers with a strong spring-training performance that included 20 strikeouts in 21 innings and a 1.00 WHIP. In four starts for Mobile he went 2-0, 1.67 with 25 whiffs and 31 baserunners allowed in 27 innings. That 1.67 ERA ranks third in the Southern League, where Corbin has spent the past two seasons notching fine strikeout (8.0 per nine) and walk (2.3 per nine) rates over 187 innings.

What Corbin lacks in raw stuff compared with Bauer (who's wrestling with a high walk rate this season) or Skaggs (who's two years younger than Corbin), he compensates for with command of the strike zone, plus lateral movement on his low-90s fastball and rapidly-developing feel for his changeup and slider. That pitchability is somewhat unexpected in light of the fact that Corbin didn't first take the mound until 2006, when he was a junior at a Central New York high school. Now he's the first prospect from Arizona's Dan Haren trade to make it to Phoenix.

Don't expect Corbin to contend for the National League strikeout crown, but do expect him to turn in more good starts than bad as the Diamondbacks sift through their rotation options this season. His stuff also would play in a high-leverage relief role because he can retire righthanded batters. Having acquired Ian Kennedy and Daniel Hudson in trades at a time when they were unproven commodities, Arizona has demonstrated a knack for scouting pitching talent in other organizations. Corbin (and Skaggs) figure to be no exceptions.