Nobody has ever said that batters will all hit for the same BAPIP. BAPIP is simply a measure of BA on balls in play. For hitters I definitely don't consider a player lucky if he has had a high BAPIP for his entire career. Further The Hardball Times has developed an xBAPIP (expected) calculator that uses a lot of different variables to determine an xBAPIP. A few of those include LD% (a really high BA on these), HR/FB% (hit the ball harder = higher BAPIP), speed (beat out IF singles), IF popups (always outs), FB% (lower BAPIP than GB's) and several others. I'm actually too lazy to use since I find 3+ seasons of BAPIP data to give me a pretty good idea if a hitter is lucky/unlucky.