He's a hard one to let go, but I think he's worth more on the transfer market than as a trainee.
My first thought was, with that JR, he'll never be more than an outside-focused SF, but while his rebounding and IS are great starting points to train from, his ID + his height make him too difficult to train as an outside-focused SF.
As a PG trainee, with that JR, you're basically adding an entire season to his training time. Which is why I suggest selling him and finding another trainee instead. MY advice would be to pop his OD once and then sell.