Actually, she was robbed - she was the aggressor all fight, Taylor playing defense, grabbing and clutching all fight, hoping for landing a lucky punch as they separated, and the # of punches thrown / landed and the quality of punches landed by Serrano was clearly superior to Taylor. Whether the head butts were intentional or not is not certain, but it seems like some of them were. Either way, the strategy to lean in with the head, and not care if the head butts inadvertently / or partially intentionally happen seemed to be evident.
Taylor has been a great champion, but tonight she clearly did not out box Serrano. She just out-duped the judges.