ElGuapo wrote on May 19
th, 2016 at 7:38am:
That being said, if you want to test yourself, slot in improved crit slash and take a run with your wolf at the dummy and see what kind of numbers your crit on. Gonna be 19-20 same as any base wolf. Now try imp-crit bludgeon. All of a sudden your 17-20.
I just finished up some testing a few mins ago. With Improved Crit: Slashing, my crit chances, indeed, only happened on a 19 or 20. I then switched out Improved Crit: Slashing for Improved Crit: Bludgeoning. Crits ONLY happened on 18-20. My guess is when they changed the way Improved Critical worked, the Wolves' Unarmed was treated the way Monk's Unarmed was treated and only increased the threat range by one.

Every 17 rolled in the Combat Log read like an 11, 15, or 6...not a critical chance.
5 Foot Step wrote on May 19
th, 2016 at 9:58am:
Better yet, read the in game description tooltip of Improved Critical Budgeoning.
Just did that. Yep, it seems only a one number increase in crit threat range was intended in Animal form. Ugh.