My prior post said there are 3 viable options for fixing this mess. It turns out there’s a 4th viable option:
Option 4: Compute the manform calculation and the traditional wereform calculation in parallel, and then use the result with the lowest fpa.
Assuming the motivation behind this change is to prevent new players from being confused when their level 1 werewolf with no IAS is slower than manform, then this is likely the best solution. It accomplishes what Blizz set out to do with the 2.4 change, unifying early-game wereform and manform attack speeds, but also leaves the current late-game builds unchanged. Additionally, unlike other options that change the IAS calculations in novel ways, this option runs no risk of unintended side-effects.