Most people are missing the point. MM did well against similar sized midgets. He would get soccer punted across the cage or Tank-tossed over the top.
He wouldn't be able to pull of most submissions because his limbs would be too short or his opponents would flex to break the attempted hold.
Could he beat some of the normal human sized competitors or smaller that were smoked in the 1st round and probably should have never entered? Maybe, maybe not. In the end, size matters.
Plus, a stick and move, run da fook away in terror strategy might be viewed as timidity.