There was a form of timing leeway QoL added when pressing Bladestorm in the original version of Cataclysm to prevent circumstances such as being crowd controlled at the same moment you pressed Bladestorm.
I don’t know the EXACT timing but if you are able to test the original Cataclysm data you should see that if you try to crowd control a warrior and he presses Bladestorm within about the first second or so of being cc’d, Bladestorm will actually break him out of it, I at the very least know this worked on stuns, Cyclone is the only CC where I believe it may not have worked.
I used this religiously to deal with Cheap Shots / Kidney Shots in the original Cataclysm, and I was playing A LOT of arenas 2650+. It will actually create some major balance problems if this is not applied in Classic with how strong Rogues and burst damage are.
It may be something devs have to be consulted for because it could’ve been that this was originally done for balancing reasons but I know they were having problems with warriors being crowd controlled DURING Bladestorm in Wrath, and that’s why this was originally done for Cata. It does not seem to be working in Classic.