I don't recall the details, but the story was to the effect that Durelle was in the hands of a coach who had some peculiar ideas about training that ultimately served to weaken rather than strengthen Durelle, in preparation for the re-match, so that he ended up unfit for the fight.
The top Canadian pugilists were an unlucky trio. The diminutive Tommy Burns became world heavyweight champion, losing the title to Jack Johnson; Burns went the full - what, twenty? rounds with Johnson, but was beaten fair and square, although Johnson required some weeks of hospitalization after. But Burns' career was destroyed by the New York sports writers, including, sadly, Jack London, who villified him for defying them and letting a black man have a crack at the championship.
And then there was George Chevalo, who gave Ali what was, by Ali's own account, the toughest fight of his life. Chevalo's subsequent career was apparently thwarted by the machinations of some Chicago gangsters, and then the rest of his life was an almost-unbelievable series of personal tragedies ...