I think both. Lucky that he had a chance to win the belt from McCall, and lucky that McCall didn't show much fire in that fight. Bruno was a beast of a man and a very good boxer, but as you say he was an 8 round fighter and you can't be a world champion long with that kind of limitation. People only saw his losses because that's what all of his big fights wound up being I'd imagine McCall was the only man he ever beat who he wasn't heavily favoured to.