I go to games early, and often see guys stretching in pairs. If they are smart, they do build leg endurance, and to a lot of sprit - jog combinations. You are absolutely right, in that basketball, hockey, soccer & soccer players are generally speaking in much better shape. I think baseball players would be better served by staying in better overall shape, but that is tough when you are spending 5 - 6 & often more hours at the ballpark each day. It's such a grueling 162 + schedule though, so I get why most don't do this. Many ride the stationary bike, but that's a different kind of leg strength. It's good, but not the best.
Instead of 'self-serving laudatory anecdotes,' I'll take the ..... " my f***ing body is a quitter" excuse.
My wife is trying to get me to yoga with her, but I find that it just makes me angry. As I understand the practice, this is not a normal response to such physical exercise? Whatever. I just find their unrelenting calm highly irritating?