I'm assuming Melvin Paz
(47477358) is the player you're referring to.
So the short answer is that his height is a significant problem.
Long answer: A 21 y/o at 6'10" would get about 50% more out of training ID and 25% more out of training SB. Additionally, probably wasn't advisable to drop $600k on a 21 y/o at $5.8k salary with only a few weeks left in the season. MVP potential is nice, but at 21 it's clear he wasn't getting adequate training. I'd offload the player and save for 18 y/o superstar+ trainees generated next season.