Being underestimated would probably make defending his students a hell of a lot easier. Unlike most of his classmates he actually had to train muscles and learn how to push his body right before it breaks. That boy is a jacked nerds and nobody can convince me otherwise

Plus, his whole experience as a hero in training was like hella intense; the muscle and combat training alone would make him a very strong quirkless person like a wrestler or a boxer. Certain skills don’t just go away just because he doesn’t have powers any more.

Small rant time: I feel like Deku bringing a UA teacher is a really good arc for his character before going back to being a hero. He has always been really good at quirk analysis and could totally help his students grow their abilities in ways kids couldn’t ever think of.