There are some very interesting things in here. First off, Meyers Leonard has an insanely high offensive rating for a rookie at 115. By comparison, Damian Lillard's offensive rating was 108, which is still a very very good, especially for a rookie. Meyers Leonard is the worst rebounder of the bunch by a long shot. Meyers is worse than all players in TRB% and Rebounds per 36 minutes.
Meyers defensive rating is 110. That is really bad. (for defensive ratings, the lower the better. 104 is about average, 100 is very good, and anything less is elite.) He also had the worse WS/48 of the bunch other than Bynum. But Bynum hardly played his rookie year. Still, his WS/48 of .097 was higher than Lillards of .088 this year.
None of these Centers were very good defensively their rookie year (though they were certainly better than Leonard), but they all improved a TON. So have no fear, the NBA coaches will give Leonard the training and fundamentals he need to become at least a solid defender. Just don't expect him to become a very good rebounder.
Lastly, I will show a comparison of the rookie centers this year (Zeller, Drummond, Leonard)
Wow. Drummond is gonna be REALLY good. Zeller, not so much. Leonard is gonna be a very good scorer, at least. It's not hard to imagine him being a 20 point per game scorer in his prime with his athleticism and skills on offense.