Nathan was booed when he took the mound in the top of the 9th inning, and then even louded after he walked the first two batters he faced to put the potential game-tying run on deck.
After Pittsburgh third baseman Josh Harrison ended the game by grounding into a double play, Nathan twice flicked his chin, which could be construed as a rude gesture.
"Both sides were frustrated," Nathan said to MLB.com. "I have 2 kids. I need to be a better example than that."
Nathan is 4-3 with a 5.11 ERA in 47 appearances in his first season with the Tigers and is tied for the Major League lead with six blown saves.
- Scooby Axson