In the post fight interview he was asked about the mouthpiece. He laughed and said it was a rookie mistake that he will correct. He said the mouthpiece didn't fit properly and he will get one better moulded to his teeth. Wore the same mouthpiece in the Garcia fight. Now you know.
He said in the post fight press conference that it didn't fit properly and was moving around all during the fight.
He probably has some lingering brain damage from the crash. Every time he gets hits decently now it's like his proprioception goes haywire for a second.