On May 20, 2006, this happened:
As it turned out, Barrett would fall out of favor next season with the Cubs after butting heads with a few members of the starting rotation and only last 37 big-league games after the 2007 season.
So, really, it's easy to see what happened. A player generally disliked by the opposition plowed over a hot head. And we get a benches-clearing brawl. Everyone wins!
On a funny, related, note, the White Sox ended up running with "Punch A.J." as their campaign slogan to get him elected to the All-Star Game via the "final vote" (where the team is set except for one last guy, chosen from a field of five).
Unheralded star of the brawl: Scott Podsednik, who got all over Barrett after the aforementioned punch.
Anyway, happy anniversay to Barrett's fist and Pierzynski's face. It was seven years ago they got together.