The biggest difference in Wilson and Cobb's career is how they were "managed." Having money behind a fighter can be the difference between a fringe contender and a journeyman. Wilson was almost 33 when he turned pro, he had no backing, taking fights as the "B" side wherever he went. He was thrown to the wolves and made a "name" for himself by going the distance with most and getting a draw with Mercer. He was fighting a who's who of the heavyweights as their "opponent." Not many who start like Wilson will ever be contenders. Cobb turned pro at 23, had enough backing to get some winnable fights, build up his record, then fought some "names" and then cashed in that record against Holmes. Cobb was well managed and probably made some good money as a "white hope" when there were few white heavyweight contenders. By the time he was the age that Wilson turned pro Cobb was being knocked down by Eddie Gregg and out by Dee Collier.
All good points maybe I should of used another fighter as an example, but everytime I think of granite chinned Heavyweights. I always think of Cobb and Wilson, which is why he was the example I first thought of.