Any chance he has been using steroids? He has beefed up a lot, and is trying to recoup from injuries. It is in no way a defense, but the trickle of information seems so different from his public image that it would almost make sense. Side effects are violent outbursts from normally non-violent individuals. I would not be suprised if it comes out somewhere along the way that he was using steroids or some other medication (either prescribed or not). Pure speculation, but I had a suspicion about this when he muscled up so much last summer. He also seemed more abrasive in team dealings last year.
He dosn't have to... before bulk up he's already established himself as one of the best in the league... so why would he take the risk with drugs? So the answer is NO.
People said Bonds and Sosa use steroids too. You can't prove that unless you test them. Kobe will not be tested by the court. So we'd never know.