If we are not talking about a peak Tunney, but the Tunney who would have been in the real world, he would have been aging fast in the early 1930's. Would a 33 year old Tunney have been able to handle a 28 yr. old Sharkey? Would a 35 year old Tunney have been able to handle a 27 year old Schmeling? A 36 or37 year old Tunney a 24 or 25 year old Baer. At his best he might have beaten all these men. But there is no reason to think he would have remained at his best. Also, all these men would have been bigger than any Tunney opponent except Dempsey and then only in the case of Schmeling.
I have seen a lot of movies with Cagney or Tracy, and neither ever did as good a job of looking unconscious as they were falling as Sharkey did in this film. Everyone enjoys scoffing, but I have not seen an actor who could do a good job of mimicking that "dead" facial expression of a fighter who has been knocked out. But Sharkey has it.