Playoffs? You kidding me?
I'll bet most minor leaguers have had playoff experience at some point in their baseball careers, whether it's at a lower level of the minors, college or high school. These are the best players on the best teams in the country
Second, I'll bet if you asked most major leaguers if they change how they play/prepare in the playoffs I'll bet they'll tell you that the atmosphere is different but they do the same stuff that worked for them in the regular season.
I just don't think you can get to professional baseball without having been in some kind of athletic pressure situation, in most cases