What do you thought when you wrote "renormalization"?
Recalculation of NT Rankings at all? I don't think there is something like this. Or if there is than ratings after renormalization looks very close to this before it (no big points differences in that time I mentioned).
But I think there should be fixation of ratings which are used for whole next 2 seasons for calculation of team strength. If it was like that it explains why all matches in first 2 seasons of U21 was worth the same amount of points (all matches at the same stage), because all team were equal for algorithm for whole 2 seasons.