Hi Phil Jackie Chan:
I can't say I am the best at putting together a team, but here are some thoughts for you to chew on. In the end, the decision to train or not to train, and how to train, is ultimately yours.
You also have a good problem - a good potential player with obvious strengths and flaws, and a decision on how to build around him. I wish I had your problem when I started out.
First, I would suggest that you try to bbmail Jelme, who is the manager for the U21 National Team. Based on the profiles of the current U21 players, he can give you advise on how to get your player to the levels needed to be an elite player.
Personally, if I had your player when I first started, I would train him a little bit on the inside skills and then sell him before he becomes 19.
why?
here are my reasons -
1) he has atrocious outside defense. As you promote, you may find this a problem. not so much in div 4 or 5, but when you get to div 3, there are lots of pivots and forwards with decent outside shooting skills that you will need to defend against.
2) it looks like your center fouls a lot. this could be combination of an aggressive nature, poor OD, and poor stamina - but as you promote and your competition gets better, it will be get harder to give him 48 minutes of training in 1 single game.
3) He has HOF potential so he will get attention from div 1-3 teams while he is young. You are in div 5, and probably don't have a level 5 or more trainer, so you will get more $$$ than the value from which you try to train him yourself.
4) He is rather short so he will train slower on the inside skills as he gets older.
5) shot-blocking is very expensive salary-wise. And lots of managers have different opinions on the value of shot-blocking, which will be reflected in his market value over time.
Either way, I would not train him too much before I try to sell him - why? because I don't think div 1-3 teams will buy him if his salary is too high and he gets too old. too low outside skills, stamina too low, too short etc. At that point, he may become too expensive for a div 3-4 team (less revenue and savings).
Personally, I think he is a good sell right now, or for even more money with just a little more training. Sell closer to playoffs if you want to maximize.
With the money you have, you can expand your arena and pick up some veterans (so many good deals right now) or other good 18-year olds to train (save your money and get just all-star potential until you can get a level 5 trainer, then go for the superstars and HOF).
The minus of it is I reckon your fan survey is going to plummet if you decide to sell. Most probably.
But in the end, it is your player, and your choice. Definitely get more advise from more experienced and better managers than myself, because you will want to make a decision that you do not regret (sell or not/how to train).
Good luck, welcome, and remember - it's a game, so have fun.