Boy, I'm not a big Biyombo fan. I saw him play 3 times in summer league, and I've caught a few of his games his year, and for what you gain defensively, you give up on the offensive side of the ball. There are times when he's just lost out there. I'd rather take a flyer on Udoh or someone of similar ilk. If all you want is a defensive stopper PG, then we should be able to draft Aaron Craft in the second round of the next draft. He and Marcus Smart are the two best defensive PG's in all of college. Semaj Christon is a very good defender as well, but he's probably going in the first round. By the way, he's a hell of a PG. He doesn't get the PR some of the others get playing at Xavior, but he's a very talented PG with good size at 6'3", and is one of the best ballhandlers in all of college.
I don't think a defensive PG off the bench helps us all that much. We already have Ray McCallum who's a very good athlete and should be able to hold his own defensively when he's in the game. We need a starting PG who can play defense and distribute the ball for 35 mins a night. Maybe Smart is the guy, but I'm a little bit wary about his ratio of shots to assists. I wasn't impressed with him last season -- didn't look good in the games that I watched -- but I should be able to watch him more this season.