so this is Beckham Phelan and he's 6'7" right?
He looks great to me, similar to the guy I just paid $1.5M for. I don't think you can make U21 since he's not "specialized" to any position, but maybe you could be in the running if you pumped more OD and there's a need at SF. I think you'd need at least 12 OD and then probably some JS or IS pops for that.
If you're focusing on club purposes then my current opinion is that you should target a build based on what you think the devs are going to do in the near future. Lately there have been a lot of fairly impactful changes to the game engine, like in this season's news there are changes to stamina and neutral tactics. IMO that increases the value of well-rounded, lower-salary players like you've got a start on there. So I'd keep training him up "evenly" inside and outside and build a solid SF. Might not be the star of the team at an NBBA level but would never be the weakest link in a 5 man group.