isshinryuronin
Senior Master
I've seen it happen more times than would be expected based on the sumo's size. Depends on the situational definition of "often." Not most of the time, but a surprisingly (30%?) high number it seems from the matches I've watched.Not often
The most obvious way superior size can win is the type of frontal force out where the big guy picks up the little guy in a front bear hug and simply carries him out of the ring. This deprives the smaller guy any chance to use technique.