Go back through the patch notes and see if it says anything about it, if not then it's an undocumented change and should then be posted in the undocumented change posts. What Galen is saying is that yes, it does less damage, but you can cast both at the same time anyways, and for single target you should be using charged chop anyways. While wind chop may have been nerfed, cc got a huge boost a while back, so your dps will be up still from the patch before the warden change. As a side note, the ROMwiki does not list a cooldown for wind chop, though I suppose that's not saying a whole lot as the 60 elites were being added by me and I have no affiliation with the site at all.