I think every one of your responses in here are great. I know, it's meant to be a joke thread, but I ain't clickin' that link. Also your comments regarding Cain and subsequent defence of those comments was perfect.
Little guys like Cruz, Edgar, Aldo...you expect a relentless work rate, because it takes far less energy for them to achieve a similar result as it does for a larger man. The amount of oxygen/kilojoules used grows exponentially with the HW mass. Ever noticed that even at WW, plenty of guys gas by the end of the third. Diaz, Condit, GSP are exceptional because they go hard for 5 rounds. That gets harder and harder the bigger a fighter is.
So while Cain was clearly tired in his JDS fight by the end of the third, there isn't a HW fighter alive that could have kept up with him until then.