Donaldson took exception to being hit by Musgrove's 94-mph fastball in the first inning and immediately approached the mound, leading to the benches clearing. Although no punches were thrown, Donaldson, Musgrove, and Pirates manager Clint Hurdle were all ejected.
Musgrove felt that Donaldson was at fault and escalated the situation in the moments after being hit.
"We've had no beef in the past until now. For him to act that way and I did nothing but stand my ground," Musgrove told reporters, according to Nubyjas Wilborn of the Pittsburgh Post-Gazette. "I hit him with the pitch and he stared at me and tried to intimidate me and I'm not going to let that happen. I looked back at him and he had a few words to say. He crossed the line and came at me. I took my hat and glove off and got ready to fight. I don't know what else you can do in that situation."
Home plate umpire Brian Gorman said Musgrove tossing his glove and hat while approaching Donaldson made him "an aggressor in a brawl" and prompted his ejection.
Donaldson, for his part, said he "wasn't really upset about being hit" and claimed he gave Musgrove an opportunity to walk away before the brief melee broke out. The pitcher disagreed with that assessment.
"He was what I was looking at, and I said, 'You.' I was doing the same thing he was doing," Musgrove said. "I barely grazed him with the pitch. There was no need for him to act that way."