Wlad wasn't that good. Not even a top p4p fighter. He did dominated a weak division. And also having an upset doesn't make you deserve FOTY. Winning one fight shouldn't make you win the fight. As primo said, pac is easily better than wlad so mayweather should be FOTY by your criteria.

If fury beat wlad earlier this year then beat wilder and got his belt I could see him getting it because he proved to be dominant in his weight class instead of just getting an upset win. Winning FOTY means that you showed your dominance. It doesn't mean you upset a good fighter.