Lets assume that young Wlad (from the Mercer fight) fights prime Mercer that fought Holyfield? Who wins and why? Reason i am picking young Wlad and not Wlad during his title reign is because i do not want to see Wlad's excessive leaning, clinching, pushing and outright illegal tactics.
The version of Wlad that you are talking about was still a work in progress...several fights before he had Manny in his corner. I can see Wlad panicking here when Mercer absorbs some of his early bombs, and is putting pressure on a tiring Wlad. Wlad completely gassed out vs. Brewster and was bombed out, and that was several fights after the version of WK used in this thread. Wlad wouldn't have been ready for an absolute prime Mercer at that point IMO. I think Mercer would survive some early abuse, and stop Wlad sometime after the 7th.
Mercer wins this by late rounds KO, he was as durable as they come. Older Wlad would win by a wide UD over prime Mercer.
I think Wlad would still win but it would be more competitive. We all saw the fight between them. Stylistically Mercer is pushing a boulder uphill. Young Wlad boxed his head off and Mercer had improved in some ways as a boxer as he got older. A younger version would have had more speed and workrate. But I don't see how that stops him from eating all the punches he'd eat. If young Mercer would win it would be the same way old Mercer would win - by gassing Wlad out with his chin. Honestly, I'm not sure he'd be able to. Mercer was light in the pants compared with Puritty and Brewster was landing significant shots in addition to weathering the storm. Merc er really didn't land much of anything besides with his sharp jab, which is something that his younger version had not developed fully.
A prime Ray Mercer MIGHT have stopped the young Wlad who lost to purity but that’s probably the only scenario where I’d give Ray a chance to win.
The version of Mercer who was an out and out, come-forward slugger, pre-Holmes, was more dangerous than the veteran golfing wonder Sanders and was a level above Brewster, too. That version of Mercer would run the young Wlad over.
If he blew his wad trying to get Ross the Boss and Brewster out of there, you have to imagine he would be huffing and puffing against Mercer, win or lose.