His guard skills are good, especially his OD, DR and PA. If possible, I recommend training his Outside Defense and Passing until he hits strong or proficient. Then move on to 1v1 Guards to increase his Handling so that he won't lose the ball as often.
If you want to continue with his guard skills, you can also train JS Guards to improve his Jump Shot. A big with a decent jumper has the ability to torch opposing bigs that have low OD.
Field goal percentage-wise, training his Inside Shot to a decent level (prolific, for example) will allow your trainee to make shots at a consistent rate (as long as he doesn't go against a defensive monster). His rebounding doesn't need to be super high in order to grab a few boards each game.