Clutching to a 4-3 lead in the top of the eighth inning on Friday night against the Phillies, Diamondbacks manager Kirk Gibson brought in lefty Oliver Perez as the Phillies were leading off with two lefties of their own in Chase Utley and Ryan Howard. Perez retired Utley on a weak fly ball to shallow left-center. Before Howard could settle into the batter’s box, Phillies manager Ryne Sandberg strode towards home plate umpire Mark Wegner to start a conversation. As Steve Berthiaume noted on the D-Backs’ TV broadcast, the conversation was about the slits in Perez’s undershirt, which may have been a distraction.

The umpires then grouped up and conferred. Wegner approached Perez on the mound and informed him that he would have to change or remove the undershirt before he could continue pitching. Annoyed, Perez stomped off of the field and yanked his button-up uniform over his head before heading into the dugout to meet the dress code.

Perez came back out and threw a warm-up pitch with the fire of a thousand angry gods, it appeared, before resuming play against Howard. If Sandberg’s concern was a tactical ploy, it worked, because Howard singled off of Perez, prompting Gibson to bring in the right-handed Brad Ziegler to face Marlon Byrd. Byrd singled to put runners on first and second, but Ziegler induced both Domonic Brown and Carlos Ruiz into grounding out to end the threat. The D-Backs would go on to win 5-4.