Intuition would say repeatedly getting bounced off and down the canvas like a basketball would be more damaging, but that might be more psychological if anything. It's not like you can isolate that fight from the literal bloodbath he endured over 10 rounds with Fundora right before. Maybe Bakhram cracked his chin, but Tszyu got dropped and hurt by Fundora unusually fast this time too. It was his team's fault for not knowing how to handle cuts and not pulling him out when he was disfigured. Fundora definitely got better, but he got nose bloodied the same as the first fight. Tszyu was damaged goods one way or another.
I feel sorry for Tim. I knew that Bakhram fight had ended his time at the top and backed Fundora by stoppage, but it's horrible to watch a fighter get broken down mentally. His corner took years off his career with their awful corner work in that fight; he should never have been sent out for round 3. It really is a brutal sport at times. I don't think Tim ever really had what it took to be a world-level guy; his best win was a cautious points decision against Mendoza, but he's completely done now, and it's probably best to call it a day.