I was trying to chest snipe in Gurubashi arena (as a 42 druid), and when the last rogue left standing started to open the chest I came out of stealth and used the Goblin Rocket Helmet.
I hit him, and he was incapacitated, but I was incapacitated for the full 30 seconds too (I had a reckless charge timer on me counting down from 30). He came out a couple seconds before me and deleted me.
I played in vanilla, and as far as I can remember this NEVER happened to me once in over a year of playing. Am I drunk or crazy? I suppose it is possible that the rogue quickly hit me with a rocket helm at the same time, but I swear he wasn’t wearing one.