this is a rather fun idea!
however, as much as i like the U21/NT landscape (i suggested a reform for it 3 seasons ago) i doubt the BB's will be able to implement it.
Not because they don't want to or because they think it's a bad idea. More because there are other more pressing problems that require solutions ;) Currently, i'm guessing that 10% of each community is interested in the U21/NT. So such stats would only be for those 10% (if they all viewed it). Don't want to belittle those 10%, but there are more pressing issues.
Still +1 for the idea! (i took pride in never losing to some nations while i was U21/NT coach, and such a thing could back up any talk that was had about it.