Pierzynski was tossed in the sixth inning with Texas ahead 2-0.
Darvish had not allowed a runner when he threw a 2-2 breaking ball with two outs to Jonathan Villar. Darvish began walking off the mound and Pierzynski started heading to the dugout, but plate umpire Ron Kulpa said it was low. Pierzynski didn’t like the call and started yelling in Kulpa’s face.
Here’s a GIF  of what happened.
Pierzynski was quickly tossed and replaced by Geovany Soto. Darvish then walked Villar, giving the Astros their first runner.
Source: Associated Press