Didn't his ex-coach say so after they went separate ways following the Ward fight ? There's an interview out there where he talks about how he thought the conditioning coach wasn't doing a good job with Dawson in the training camp leading to the Ward fight. I could be wrong but I think the Miranda sparring session (KO one) is mentioned in the interview.
dawson ex trainer scully posts ont he scene, he confirmed he was knocked down and said stuff like that should stay in the gym,.
This has already been confirmed. He wasn't knocked out, but he was knocked down and his bell rung. This has been confirmed by multiple first party persons.