Of those with roster spots locked up, only Chafin is left-handed, which could factor into who wins the final spot, if D-backs manager Chip Hale decides he wants two lefties in the bullpen.
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"It would be a luxury," Hale said of having a pair of lefties. "Most teams, when you design it, you'd like a lefty earlier in the game and a lefty late in the game."
Chafin is not a prototypical left-handed specialist, because he is able to get righties out as well. That ability makes him valuable as a pitcher who can pitch a full inning rather than just coming on for one batter.
Last season Chafin held lefties to a .182 mark while righties hit .225 against him.
"The thing about Chaf is he can get both righties and lefties out," Hale said. "He's really developing his breaking ball. That's one thing that they're working on this spring, and with that breaking ball improving every time, he becomes such a weapon against lefties. He already gets righties out, which most lefties don't do."
So if the D-backs had a left-handed specialist to go along with Chafin, they could use the specialist for just one batter and Chafin for longer stretches.
The D-backs have a lot of lefties in camp, including Matt Reynolds, Wesley Wright, Daniel Gibson, Keith Hessler, Will Locante, Scott Rice and Adam Loewen.
Hessler, Wright and Rice appear to be more strict lefty specialists with righties hitting them at a much greater rate. There's not much difference between righties and lefties with it comes to Reynolds. Locante and Gibson are both young pitchers who may need more seasoning, and Loewen is a bit of a wild card given his pitcher-to-position player-back-to-pitcher career track.
It's also possible that the D-backs won't carry a second lefty.
"If we feel like we have a righty that can get lefties out and we feel like he's the better option, we would go with that," Hale said.
Right-handed setup men Hudson and Clippard both pitched well against lefties. Hudson kept them to a .186 mark last year while righties hit him at a .291 clip and Clippard also had better numbers against lefties (.137) than righties (.242) last year and in his career.
The fact they pitch well against lefties might make it less important for the team to have a second lefty and open the door for a right-hander such as Evan Marshall, Enrique Burgos or Silvino Bracho.