He is dead right. Lamont Brewster knocked out Wlad. Before emmanuel got a hold of him, he was just a big tall guy with suspect stamina and chin. In the late 1960s and early 1970s, there was a definite bias against guys as big as the Ks. They were considered too awkward and uncoordinated to be good fighters. Vitali would have been Buddy Baer; they were about the same size, liked to mix it up, though I would guess that Baer hit harder.
there is an idea that seems to be very popular that just because a guy is big, he hits hard, that because he is larger he necessarily hits harder than other less large guys. This is not true. This has been demonstrated many times. And when you are fighting smarter guys, like Shavers did, you are less likely to hit them. It is very easy to keep a guy at the end of your jab when his whole idea of how to close distance is to put his gloves in front of his face and walk forward.
I think Shavers would beat Vitali; he would kill the version that engaged in that 2nd rate amateur bout with Lennox Lewis. He would beat the pre-Stewart version of Wlad. The 'new and improved' version would be able, more than likely, to keep distance, keep Shavers at the end of his punches. And earnie would tire and get stopped.