I liked Oly until I went to the Wizards game (here in Washington) on December 27th. On TV, you can't see how much he loses his man all the time. The difference between him and Bass in defensive positioning was night and day. It's still his second year in the NBA, and he really wasn't asked to do that at all in college (and in high school he was a pg and didn't need to know how to defend the post), so I hope he can learn. But as of now, he has a lot to learn, and is a detriment on the floor. I also think his defense is getting to his offense -- partly confidence, and partly his constant foul trouble is keeping him from getting any rhythm.
He doesn't need to be anything better than mediocre on defense if his offense comes back to be a useful player -- no one ever projected him as a defensive stopper. He just needs to not be terrible.