Why would you want to have (and probably display?) a lower rank, actually? I think it would only make sense if those badges would stack (i.e. we’d get the same badges next year and their counter increases) but right now the year is included in the badge title, so stacking doesn’t really make sense… 
But I agree in general: if we had generic badges with the bingo count and if they’d stack, then the lower ranks should be assigned as well.
