I'm not seeing things wrong am I? He is a guard. Not a small forward or big. ID, shot-blocking and Rebounding are not that important on most guards. The only thing I would advise him to train out of those four skills that you mentioned is Inside shot (which can be trained up quickly with 1v1 for forwards). You have not even played this game for a full season I don't believe, so I know you are just trying to give advice based on what you know but It's not the best to advise other managers to train their 6'0" guard in rebounding and inside D, especially when they could easily use some more OD and passing (which is crucial for guards). Not the best advice, but I suppose if he likes your idea then he can run with it and train rebounding up to legendary.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs