Agreed with your thinking, and I don't know the right answer but I'll try throwing a few things at the wall.... would FG% work better than ppg to encourage the player to take quality shots? Or assists or a team stat so they're not just playing for themselves?I have not seen anything to indicate that NIL contracts are any different from any other contracts. As such, they should be able to contain whatever conditions the two sides agree upon.
When NIL first started, I thought about performance bonuses. Then I thought about what they could do to team chemistry. What does the player with a bonus for averaging 10pts/game do if they are not comfortably averaging more than 10pts - pass to the open person or take the contested shot? The same type of non-team play distortions seemed to come up for pretty much every stat I could think of except defensive rebounding. I'm probably missing something there. Bonuses for average minutes wouldn't affect their on court play. It may sour the player/coach relationship -- you cost me money by not playing me enough.
I do think that multi-year contracts, with growing payments, or claw back clauses if the player decides to leave while the coaches still want them, might work. Bonuses for where they place in the BTT regular season, BTT tournament, and NCAAs also may work.
A bonus for average minutes played might work if they actually get benched for not running the offense but if coach doesn't have a quality alternative to play they might not get benched until the last game of the season