I don't understand how posters on this board think TJ is a good defensive player. I really like his offense, but his defense is certainly below average. I'm not saying to take him out of the starting lineup, but you should pair him with a good defensive center that could block shots.
In referring to his lack of size, he does not play like a 6'9" player on defense if that is even his true height. He's not long, and doesn't block shots. He gets out maneuvered and outmuscled in the low post on defense. If he is our main defensive front court force next year, expect a long season.