Tensions have been high between the Cubs and Pirates this series.
Chicago first baseman Anthony Rizzo had a controversial slide into Pittsburgh catcher Elias Diaz on Monday that the league said should have been ruled interference on Rizzo.
Then on Wednesday, the benches cleared after Pirates starter Joe Musgrove slid into Javier Baez at second base. Musgrove's momentum took him into Baez and he couldn't get the throw to first for the double play.
Musgrove walked off, but Baez started saying something and Musgrove turned around. Soon the benches and bullpens emptied. There were no punches, and umpires ruled the slide didn't violate rules.
The two teams will meet again for a series in Chicago on June 8–10.