How many weeks since you got a pop? I recently bought a similar Star potential SG whose salary is already over 30k. I'm trying to get one more pop on OD, trained him for 1 week only so there might be hope for him yet. Besides he's 26 so probably 2-4 weeks is standard even with high sublevels.
The thing I don't get about the caps is if its got anything to do with position or is purely a net skill cap. If its purely a skill cap do all skills count - including, say, SB for PGs? On the other hand if it depends on position then I'd think 1 pop here or 1 pop there could change an SF into an SG and if he had the right combination of skills for the SG position he'd suddenly be capped. So what is the cap based on exactly?