Since yesterday’s patch, Windfury procs are now yellow damage and show up in the combat log as ‘Windfury Weapon’, similar to how Windfury works in TBC.
If Windfury is now indeed a special (yellow) attack, that will of course affect the damage output because special attacks cannot glance.
One thing that does not work anymore is getting guaranteed crits on sitting characters. The auto-hit will crit (and the Stormstrike if used) but not the Windfury attack.
Another negative side effect of this is that the proc animation is now the cast animation that normally happens when you apply windfury to your weapon instead of the multi-hit animation that should play. That kinda breaks the feeling of playing the class.
This is a massive undocumented change to the game or a bug.