I agree with you about Foreman-Frazier II,as Joe was totally spent after Manilla,but Ali and Frazier still had a lot to offer at the time of their second and third fights.
It is certainly true that Ali-Frazier II and III were good/great fights between two ATGs who gave it their all, and still had plenty to give. It was nearly three years from the FOTC and Ali-Frazier II. In the former, we had two undefeated heavyweight champions fighting for the undisputed title and the anticipation of this fight was off the charts. Anticipation for a rematch remained very high. Then rumors came on that Frazier was a very sick man. Jose Torres wrote an article in Boxing Illustrated entitled "Is Joe Frazier Fit to Fight?" Joe's easy title defenses in 1972 and his destruction by Foreman if anything gave credence to these rumors. In March, 1973, Ali lost to Norton in the jaw-breaker fight. Dick Young, sportswriter for the New York Daily News wrote at the time"... a Frazier-Ali rematch would be strictly bush league now." Frazier then won a good victory over Joe Bugner, but was wobbled by the comparatively light-hitting Brit. Then Ali squeaked by Norton in the rematch. So by January 1974, neither Frazier nor Ali were champions, and neither were undefeated. The fight was still a good sell, but had none of the electric anticipation of their first battle. In the Ali rematch, and later in Quarry II, Joe showed that he was in fact a healthy fighter although past his best. Although Manila is remembered as an all-time classic, few gave Joe much chance of winning and there was not that much anticipation of that fight. So in terms of antipation and potential for surpassing the purses realized in the rematches, I believe it would have been better had the rematch(es) taken place in late '71 through '72.
