Chafin was recalled by the Diamondbacks on Wednesday.
The left-hander struggled during his earlier stint with the Diamondbacks this season, working a 9.00 ERA with 34 strikeouts and 19 walks across 44.5 innings of work. However, he turned things around a bit at Triple-A Reno, throwing 7.2 scoreless innings over five separate appearances, including one start. He'll join the Diamondbacks on Wednesday, taking the roster spot of Zac Curtis.