Even the addition of Chafin, the Tigers are pretty thin in their organization when it comes to left-handed relievers, and really, left-handed arms in general. So if something were to happen to either Chafin or Tyler Holton, Vasquez would likely be the first one to get a look.
Vasquez had a 2.27 for the Phillies last season before he was DFA'd, which was a surprise to some. But the 4.29 FIP and overall lack of a strikeout pitch told a different story.
When he was claimed by the Tigers, he was immediately inserted into that kind of LOOGY role. The results weren't pretty. He had an 8.31 ERA and his BB/9 of 9.3 was identical to his K/9 in 12 games. Yuck.
His primary pitch is a big, sweeping slider, which can be effective if he throws his fastball for strikes. Sadly, the reason he throws his slider so much is that his fastball averages about 88 mph, which just doesn't cut it in today's game.
With that being said, he's still probably the best backup plan should something happen to either Holton or Chafin. Joey Wentz could conceivably win a spot as well, especially since he's out of options, but he's a similar spot as Vasquez. He's a lefty who has trouble throwing strikes consistently.
It would likely take an injury, but Vasquez is a name to watch for the bullpen.