Interesting theory!
I just ran some numbers on your theory and maybe you're on to something!
Top 3 teams in terms of swinging at the first pitch
AL
Toronto
Tampa Bay
Texas
Runs per game scored in the AL
1. Tampa Bay
6. Toronto
7. Texas
It doesn't hold water in the NL... but maybe you're on to something if you can refine the theory a bit!
I heard a theory one time and I don't know if it is really true or not that teams in the AL are quicker to change due to having to find interesting ways to keep up with the Yankees and Red Sox. So AL hitting coaches might have adapted to the fact that pitchers are now basically robots throwing certain pitches in certian counts for strikes or balls the coaches in the NL might not have caught on since there is more competitive balance.
I had a Poli Sci professor that always said, "History may be writen by the winners, but it is made by the losers." Basically that the people that are losing now are going to figure out a way to win.
