Jailen Peguero

Peguero has proven himself able to retire Triple-A hitters, but getting outs in the big leagues hasn't come as easily for him thus far. The D-Backs gave him 18 appearances after a late-season callup from Tucson and his 9:13 K:BB ratio comes as little surprise given his past struggles with command. Arizona's late-inning bullpen slots are pretty much locked down heading into spring training, so he'll need to open some eyes and sharpen the command if he's going to stick in a middle-relief role.

The sub-1.00 ERA catches your eye, but his peripherals deteriorated at Triple-A, and even at his best he walks too many guys. He's basically Jorge Julio, someone who might save 30 games one day, driving you crazy all the while.