Shooting isn't everything. He can just focus on OD for the whole season and get that up to a very high level and sell for heaps. Also the elastic effect will cause JR to train faster so maybe it might take only 2 weeks to pop up. With OD training and keeping all guard skills balanced for this season next season he can focus on JR which should train quick with the elastic effect.
I had an SF, every skill over mediocre besides passing which was atrocious. When he was 19 i decide to train it. I got 4 pops in a row and went to mediocre in 4 weeks. Maybe sublevel was high i don't know. I then sold him for 3 million.
So i suggest training mainly OD and some passing, one on one and JS for the season then next season train JR and see what happens. You can not waste such a good player, he won't be the best PG, but he will be a decent one that can get him through div5 and maybe even div4.
You are only getting OD up to respectable? I have a player like yours, now 19 and he has all guard skills over mediocre and Od at proficent. Train OD the most this season then focus on passing and handling and driving.