This is a two part question.

I was going to toss this in the "Ask a Trainer" section, but I figured it would be just as suitable here. What do coaches and analyst mean exactly when they say "he's too small for this class" or "he's too small for X guy"?

Also, when there is a significant disparity in height (first thing that comes to mind is Margarito v Pacquiao) what are the advantages/disadvantages for the shorter fighter? Vice versa for the taller fighter.

What are the disadvantages exactly? Is it obvious?

Thank you for your time!