No one who did that well in the HW division can ever be accused of having a glass draw. Morrison's style opened him up to big round house punches. He had a better than average chin IMO.
Prior to Ray Mercer, Morrison had 28-fights, all wins. Not a backward step in any one of them. No shakes, quivers or wobbles.
Tommy Morrison's style, of it's either you or me was his weakness. The 'open style' just left him vulnerable to solid punches. One of his sparring partners, Anthony Wade said, Tommy has the attitude of 'I'll try to knock you out, and you try to knock me out'. 'He isn't afraid of getting hit or knocked out like most of the other heavyweights, thats what makes his fights exciting.'
Morrison was also a quitter when things got tough. Watch the Bentt fight, tommy went down on his own the last two times.