No he's talking about whatever the imp equivalent of combat trance is.
Right now Ataru Form has a 30% chance to proc opportune attack and 100% chance to proc combat trance.
While combat trance is active Blade Storm is an auto-crit.
In 2.0 Combat Trance is tied to opportune attack, so only a 30% chance to proc combat trance, and the autocrit that comes with it (though now Combat Trance gives you your focus back when you Blade Storm).
That ain't a small change. That's a huge nerf to Combat Burst.
Meanwhile, smash has undergone a rebalance at worst. Smash hits a bit less harder, but everything else hits a lot harder.
I actually didn't notice this since I still always crit on dummies on the PTS, which in hind-sight was due to a degree of luck; if unlucky this will make your initial burst take longer to set up but all subsequent bursts will be easy (plenty of proc chances). Due to this change we get a 10% buff to Blade Storm.
We also get Hand of Justice, Contemplation & a lower GCD on everything with Zen. It's a bigger burst that takes longer to set up which I think is very fitting for Combat/Carnage.