Mac Foster was very talented and showed a lot of promise. He kayoed Thad Spencer on May 20 1969, in round 1, then he kayoed a worn Cleveland Williams on Nov 18 1969, then came his defeats to Jerry Quarry and Muhammad Ali. Foster was a very heavy punching heavyweight. But when it came to fighting the higher echelon of the heavyweight division, he could not get the job done.
Foster was a very hard puncher, but like Lyle and other big punchers overrelied on his power and paid for it when he fought a complete fighter like Quarry, who easily neutralized his power just like he later did with both Lyle and Shavers.
Foster reminds me a bit of Frank Bruno. Against anyone who was on the way down or slightly mediocre he looked terrific but against an opponent with the full set of tools he was shown to be really quite basic.
I believe he suffered a concussion against Muhammad Ali in Tokyo, Japan on April 1 1972, losing a unanimous decision.
I just watched the Quarry fight recently and I was impressed by him even in defeat. He had a nice left jab and the fight was close at the time of the stoppage though Jerry had taken control by that point. He marked up Jerry and actually rocked Quarry with a big right hand in round 3 I think it was that caused Jerry's knees to dip before he recovered (I was half impressed with Quarry’s chin too the guy was rock). All up a good quality fight that showed the difference between a good fringe contender (Foster) and a legitimate contender (Quarry).
Interestingly, Ring, the WBC, and Boxing Illustrated all had Foster as their #1 contender going into the Quarry fight. Jerry was somewhere between #4 and #6, depending on the rankings. But with hindsight, I definitely see your point. I think Quarry took a lot of Foster's desire. After the Quarry fight, Mac usually weighed at least 10 lbs. more than he had for his bouts before the Quarry fight. The Ali fight is an exception to this. But after Quarry, or more accurately Ali, Foster was losing to guys he probably shouldn't have lost to and didn't seem to have the commitment he'd had earlier in his career.
Nobody wanted to fite Foster, he was up and coming 24-0, then record 24 knockouts, Cosell as usual was high on him, Joe Frazier said Quarry was gonna hit Foster with everything and he did, Ferocious avalanche of punches, and Foster just was not the same, I think he was never decked again the rest of his career like 30-6 (30 knockouts) and he was still in the top ten when going 15 rounds with Ali in Japan