He's one of the strongest hitters ever. His lack of ability to box and find openings is what limited him, not his power.
No, Baer's right is not stronger than Shaver's right. He probably hit harder than Cleveland Williams, but not Liston.
I think Baer hit harder with one punch than Liston!Baer maybe pinched wild but his KOs looks way more scary than Liston
It seems plausible to my mind, but honestly I have absolutely no idea and I don't think anyone else does either. A couple years ago I posted a video of various boxers and MMA fighters hitting PSI machines, and the scores were very surprising, so much so It casts serious doubt in my mind on the legitimacy of those machines. Based on the small "cohort" in the video the boxers did seem to hit significantly harder than the MMA guys, which is exactly what I what would expect, but the difference between light heavyweights and heavyweights (including Joshua") was much, much smaller than I would expect or even can believe without much stronger evidence. (One of the keys to being rational is to be especially skeptical of the conclusions you find most welcome.)
