Chafin (0-1, 6.75 ERA) had been pitching well since he was recalled from Triple-A on June 15. In nine appearances since then, the left-hander has pitched 5 2/3 hitless innings, allowing just one unearned run and lowering his season ERA by more than two runs.
"I'm not worried about it, I know I'll be able to get right back to where I was," Chafin said. "Just a little bit of tightness built up. I don't know if it could be an accumulation of last year, going into the bullpen for the first time, having a whole bunch of outings, but it's just one of those things. It is what it is right now and we're doing everything we can to get it right."
Leone is 4-2 with a 3.86 ERA in 29 games for Reno this season. He has made three appearances for the D-backs, allowing four earned runs over three innings.
Curtis had his first stint in the Majors from April 30-June 14, posting a 5.23 ERA over 14 appearances. Since then, he had a 2.57 ERA in seven games with Mobile.
Jake Rill is a reporter for MLB.com based in Phoenix. This story was not subject to the approval of Major League Baseball or its clubs.