He was past his prime. Didn't have any tune up fights after a long lay off, he performed much better against Holyfield because he had 5 tune ups and defeated a good fighter in Ray Mercer before facing Holyfield. Tyson was at his peak. His heart wasn't really in it, just there for a payday.
Despite what he otherwise might claim, Holmes did NOT want to be there that night; when he entered the ring and during the intros, I saw something I'd never seen before with him - doubt. There was none of the usual air of intent he had in his earlier career, when - in shape or not - he was there to do a job, and he'd do it to the best of his ability. Ray Leonard put it very well when he was prepping for Hagler - after years of not getting punched in the face for a living, it takes a while to get used to it again. He got ready for it by training with championship-level sparring and getting hit repeatedly. When Tyson rushed out, Larry was not at all ready for the onslaught. Any training he may or may not have done wasn't enough to make up for three years out of the ring. Experience kicked in, he managed to survive, and eventually some of his old gumption showed itself - putting the jab out there (but not with the authority it had ten years earlier), clinching when he could, but it wasn't enough. In his prime, it would have been a great brawl, 50/50 pick 'em. He HAD a great jab, and it still showed up on occasion in later fights when he was better prepared, but he wasn't who he was ... none of us are!