Earnie Shavers' Power Quotes- An Explanation

I think Sonny Liston was in his prime when he failed to stop Bert Whitehust (2x) and Marty Marshall in the 3rd fight. He's a hard one to gauge though because his opponents were light heavies and small cruiserweights by todays standards. There not much bigger than the guys Artur Beterbiev has been brutally knocking out and nobody is arguing he is a huge puncher by heavyweight standards.

In evaluating power you have to look at who guys fail to kayo. The argument has been put forward that Shavers failed to stop certain guys due to lack of skill to go with his power but was he really less skilled than say Ruddock or Wilder? What leads people to believe he lacked finishing skills?