ok. i am going to sound very philosopical (again) and might not answer your question the way you would like to have it...
You are asking questions that cant be answered if you ask me. I have the feeling from the way you are asking (excuse me when I am terribly wrong) that like me you are playing hattrick as well. The first thing you have to understand is that this is not hattrick. Where players only need ONE skill and perhaps a sub skill at low level.
In buzzerbeater there is no right or wrong...All skills are good to have. It all depends on the tactics you are using and who you are playing. I am not a pro when it comes to basketball, but if you ask 100 people how they would train their guards in this game, you have a good chance to get 100 different answers. Also, I am not sure how important positions are. I believe (havent tested this yet) that Playing with 3 guards and an outside based defense and attack or playing with 3 PF/Centers and an inside based defense and attack is very much possbile too. Maybe even with 4 guards for the 1st option and 4 PF/Centers for the second option, works too. I think it all depends on your tactics and your oponents tactics. The very good teams, have very all round players for all positions, but if you are starting it is a huge puzzle every game to put the right guy on the right spot on the pitch...
I am training guards. I am first training OD, because this is the slowest to train, but in the end I will train all 6 skills I think are the most important for guards. JS, JR, OD, HD, DR and PS. Off course when you train Centers they need Rebounding and Inside Defence the most and perhaps some ID(again based on tactics etc), but again if you ask 100 different people they will all say different things on what sub skills to train and some dont even train sub skills.
I think a more balanced player in this game (compared to hattrick) is a lot more powerfull than a single skilled or only a few skills trained player. But I am sure you find many people that would disagree with me...
What you should do for yourself is, to create a training plan, look at what skills your players need for the tactics you are going to use in the future and train the skills these players lack.
this is a great game, but if you seriously want to build a very strong team. you will need a lot off time to plan ahead and be patient, it will take time before your players become superstars, simply because they need many skills...
ps with regards to the player you showed us, I think his OD is a bit low. But than if you never play 3-2, i think it is less important to train it. Driving I think is important for your SG, because they will be the scoring guys for your team and you dont want to miss the couple driving layups every game they get.