Windspeaker's Blessing overnerfed early game?

Just doing extremely simple math here; Windspeaker's Blessing new armour/MR bonus is equal to if you had: 27-147 armour (so weaker early, stronger late on squishies and weaker late on tanks) and if you had 13-73 MR (Why so low early?) I don't have a problem with the final values; those seem good. But why start so low, especially for the magic resist? I think it'd be better if it was 4-11 for MR, and maybe 6-22 for armour. If the problem was late game, it doesn't seem to make sense to hit the early game numbers so hard. Now, maybe that doesn't matter much. But it still seems odd to me.