I like the idea of the award, I don't quite like the change of the potential.
I think ROY could "just" boost merchandise and maybe ticket selling (and add a trophy to your team) and that would be enough for me.
+1
I think the more challenging component would be deciding on the criteria to determine who wins the award...
I think that for the criteria we could just use the same system already in place for MVP, but restrict it only to 18-19yo rookies.
I don't really know how to MVP voting/choice works in detail, but I think it would be easy for the developers to just use that at the beginning.