Your analysis seems to indicate that players can't improve with experience in the Big Leagues.
Some players do have consistently higher than average BABIP - http://www.smartfantasybaseball.com/2012/12/babip/#more-30. You could use his expected BABIP based on his percentage of line drives - http://www.beyondtheboxscore.com/2008/6/25/558256/do-fast-players-get-more-h. Pillar seems to have a high percentage of line drives so he should have a higher than average BABIP.
In any case, I believe in the saying there are "lies, damned lies, and statistics". I have taken a few university level statistics courses and I don't want to turn baseball into a complicated statistical analysis. I will continue to believe that players like Kevin Pillar have the potential to become future stars. There are players that I enjoy watching for one reason or another, Pillar is one because he started as an underdog, Goins is another because I enjoy his defensive abilities, Brett Lawrie is another because I enjoy his intensitity and because he is a Canadian and former Blue Jay. There are others such as Colabello who I root for, because of his perserverance shown by all his years in the low minor leagues.
In any case, baseball is meant to be fun to play and watch, so I plan to enjoy it instead of treating it like a university statistics course.