What he did in college isn’t translatable to the NBA. I’ve watched a lot of his games in the NBA.
IMO, in a contract year, Grant tried to show more of a bag in regular season games with pump fakes taking the ball to the rim or post.
It went so poorly he got benched and a few DNP for it. When he got minutes again, he quit the shenanigans and went back to just shooting 3’s, where he is effective.
Post Defenders are much taller and better in the NBA. And Grant is short.
Team defense is better in the NBA. So if you take your time trying to post up you can get doubled real fast, trapped and a turnover forced. So you gotta either be able to shoot the fadeaway in the moment (he isn’t tall enough) or pass out of it (he has never demonstrated that skill)