Why couldn't Bob Foster carry his power to heavyweight or even cruiser?

Foster could be argued to be the hardest punching light heavy of all time. However, his power seemed to fade even against men who would by modern standards be considered small cruiser weights. On the other hand, guys like Michael Spinks or Archie Moore would still be considering lethal punchers against 180-199 pound cruisers.

 

Bird bones?

 

He could punch lots, Ali said he hit like a mule and he has some "heavyweights" on his resume to prove it. But no big boy worth their salt is going to let him stalk and have his way. They're going to show him what difference 35+lbs can make.

On Spinks and Moore's success. They were bigger, trickier and had much better styles to fight against opponents bigger than themselves.

 

Foster stopped11 men scaling from 190lbs to 215lbs,of course they were journeymen,but still decent sized heavies for their era.
Beltin Bob did not have the frame to absorb punches from heavies who could bang and had that extra bit of class.A comparable puncher like Moore had the physique to do so.
Fitzsimmons is a legendary puncher but ,for the most part ,he wasn't knocking over men 190/215lbs.
Perhaps if Foster had been around back in Fitz's time he might have carved himself a comparable niche? Might make a good thread?

 

What 190-199 pound cruisers can you put forth as an example of Spinks being considered a lethal puncher against that weight bracket?

 

Funny you brought this up as I was watching a Foster defense at from MSG and Dunphy was announcing and said Foster's body type and style reminded many of the then old timers of Bob Fitzsimmons ...

 

None but he did floor 235 pound Cooney multiple times and stopped a Euro level modern sized heavy. I don't think it's too much of a stretch to say he could bombs away a 190 something pound fighter

 

Well there's a lot of context to be had with those two wins. He hit Cooney, who had quite an average chin so many times flush he should have died 5 times over yet he finished on his feet and quite coherent. It's safe to say the Euro heavy wasn't much in the durability stakes. Foster knocked out similar level foes.