Apparently Diablo 3 director Jay Wilson didn't like how Ground Stomp was working on his Barbarian at higher levels, so the upcoming 1.0.5 patch will buff the way CC is handled in the game. But why wait until now to fix it? Blizzard said the issue wasn't deemed as important to address as the Paragon system and legendary items upgrade in the previous patch.
According to a developer post by senior technical game designer Wyatt Chang, the new system will be based on the number of seconds an elite monster was cc'd for and translated into a CC resistance, with a cap based on the difficulty mode the player was in. So a monster hit by a wizard's frost nova an immobilized for three seconds would then have a 30 percent resistance. In co-op, a witch doctor could add a Horrify for four seconds, but it would only last for 2.8 seconds because of the resistance. The Elite's resistance would then rise to 58 percent resistance. That resistance will drop by by 10 percent for every second the monster is not cc'd.
Resistances are capped at 35 percent in Normal, 50 percent in Nightmare, and 65 percent in Hell and Inferno. While it all sounds rather technical, the post goes into extensive detail on the applications and how they new crowd control formula will be applied in various scenarios.