How Many Is Too Many?
For the vast majority of the history of baseball, most teams wore just one type of cap per season. In the mid-19th century, "Road/Away" game caps began to appear. Then "alternate' caps and "spring training/batting practice" caps. In the 90s came patches on the caps of players in the All-Star game and on the caps of teams in the World Series, which gave birth to patches on caps for the post-season in general. Since then, we've seen patches on caps for multiple reasons, most notably retiring Yankees players and an American flag patch on 9/11.