triboy, I just don't see how you can be so sure that Olynyk will be better defendively than Bargs. I watched him in college and he was poor to average, at that level, defensively, given the level of talent he played most of the time. In the Summer League he was no better except for some come from behind blocks on fast breaks.
His pick and roll defense is just poor. He's not strong enough or physical enough to guard bigger stronger players one on one down low as he often gets moved off the block. His foot speed laterally is not good enough to guard PFs on the perimeter and if he has to switch or rotate, a SF, SG or PG will just blow by him.
He's smart so he will get professional rotational defenses but who knows if he will arrive there on time to draw a charge or deflect a pass. He's also, very very far from being a rim protector because of a lack of ups and wingspan.
I've seen him play 4-5 times in college and every Summer League game. He is not a good defensive player and if he fails in the pros and busts out, still a very good possibility, it will be because of his defense and an inability to get his shot off versus average or better defensively, NBA PFs.