"It was just tight after every inning," Brault said. "And in that fifth inning, I wasn't able to get to the point where I needed to be. It was obvious seeing my velocity drop."
Brault, coming off a June in which he posted a 2.52 ERA after injuries forced him to join Pittsburgh's starting rotation full-time, is 3-1 with a 4.15 ERA in 15 appearances (nine starts) this season.
The Pirates made a series of other moves to their pitching staff, placing Trevor Williams on the paternity list, optioning right-hander Dovydas Neverauskas to Triple-A Indianapolis and recalling right-handers Dario Agrazal, Montana DuRapau and Luis Escobar from Indianapolis.
The Associated Press contributed to this report.