I don't think you can have too much defense, as long as you are some semblance of an offensive threat. The Pistons never really had an elite scorer, but everybody and contributed and the defense was astounding.
I think the main question-- and I completely defer, because I don't follow college ball-- is whether Anthony Davis will be a quality all around defensive player, which it sounds like is the case. If he was some kind of blocking specialist and nothing else, then that might be going overboard. However, Davis seems like he has the kind of athleticism to be a fantastic 4 and let BB play a slightly smallish 5.
I'm also wondering if BB is still growing.
I'm not as concerned about acquiring a scorer. You can find a guy who can get you 20 points if everything else is in place.