I missed the game, but from the way people are talking, it does sound like he's showed that his rebounding ability needs work.
I know a lot of people, me included, fell in love with his flashes of rim protection with all the blocks that we immediately wanted to give him more minutes, and I suppose I still think that...but outside of his rim protection, the rest of his game (offense, rebounding, etc.) admittedly needs a lot of work.