Coming down to the wire on this guy, but I plan to make him the cornerstone of my team, along with:
I am not sure what you mean by this but don't stop training this guy. He is no where close to done or capped. I am currently training a 24 year old and will likely train him again next season, yes they train slower but it is well worth it.
As for advice other than simply training them. I would agree that they are all solid defenders so now is the time to give them some offensive up side. Train JS, JR, Passing and if you so desire a few interior skills never hurt.
Cheers and good luck!