Personally, I don't see much of a case for the fight being stopped. Brock covered for a looong time, yes, but he always responded to the refs calls for more activity, fought to establish wrist control, and made efforts to get Carwin off of him. And bear in mind, he wasn't saved by the bell, Carwin was off him and Lesnar was attempting another takedown before the end of the round. It wasn't like Brock was lying prone the entire time.
Anyways, came away heavily impressed with both fighters. Even though Carwin's had twice as many fights as Brock, it just came off how RAW he looked, at least to me. He's had so many easy first round wins, I don't think he ever had his weaknesses exposed for him to work on. Brock, meanwhile, with the Mir and Couture fights, was given a lot to work on, and even if his standing strikes still aren't excellent, he learned a lot. In fact, this fight had me flashing back to Lesnar vs. Mir 1.