I wonder if Denman's performance - until four out - illustrates the fine line between full fitness and race-winning fitness for the very top horses.
I've noticed on the Flat that most proper G1 horses fail to hit 126 on their first run after an absence, even though they might win. I suppose trainers could get them fit if they really needed to but don't.
Paul Nicholls said on Saturday he really thought MM would win at Cheltenham so, accepting that he hadn't picked up on the broken rib, he maybe had MM fit enough to take care of the opposition but maybe not show his best form.
Then if anything goes wrong the horse becomes very vulnerable.
In terms of ability, Denman was so far ahead of his opponents the other day, it's probably safe to presume he wasn't anywhere near fit. Just fit enough to win. And maybe they just didn't get him fit enough.