With the move, the Cubs' already-strong starting rotation stands to get better. Entering Saturday's action, Cubs' starters had a 3.56 ERA, good for a tie for sixth in the majors with the Rangers -- trailing the Cardinals, Nationals, Reds, White Sox and Tigers.
While Villanueva got off to an excellent start, his work of late likely made the decision to move him to the bullpen easy for the Cubs. In his last four starts, Villanueva was 0-3 with a 6.94 ERA while allowing a .919 OPS. Still, the righty will help the Cubs out of the bullpen, as he's been better throughout his career as a reliever.
Garza, 29, is 15-17 with a 3.52 ERA, 1.23 WHIP and 293 strikeouts in 301 2/3 innings pitched in two seasons for the Cubs. He has been out for all of 2013 with a lat injury that he suffered early in spring training.
Garza has been excellent in four rehab starts, allowing only two earned runs in 15 1/3 innings (1.17 ERA) with a 0.91 WHIP.
Should Garza prove healthy and effective, it would set the stage for a Cubs' decision. He's a free agent after this season, so he could be an attractive trading chip prior to the July 31 deadline, but, alternatively, the Cubs could decide to make him part of the future core and sign him to an extension.