Grinz isn't actually smiling.

He's got a nervous tick that causes him to make grimaces when he gets
aggrivated. Unwary opponents are sometimes mesmerized by his big
sharp-toothed "grin", but quickly realize their mistake when Grinz'
big fists flies in from the wide zones.

Four games in, and Grinz still isn't getting it. This boy's got no talent after all, it seems...