Since the beginning ESO has had issues with CC mechanics such as root preventing breakout while also cced etc. Some of these issue are commonly caused by/compounded by server lag in whatever cyrodiil's main server is at the time (wabbajack, vivec, etc). What's currently plaguing pvp is animations preventing actions. The amount of unbreakable control affects is at the highest I've seen and I've played this game since the start. This needs to be priority to address for Zos above other features/fixes.
Some examples of animations interfering with intended breakout mechanics:
#1 offender is timestop
Depending on what state you are currently in or what has hit you recently it can take 1-2 seconds extra to breakout of this ability or breakout can be entirely prevented. If the channel finished while you are in mid dodge roll, initiating block, int he process of breaking out of a different CC effect, ETC.. There are multiple other scenarios where breakout is delayed or prevented.
#2 is rune cage
I am totally cool with rune cage meteor being a killshot. But there needs to be a tiny window where if the player reacts perfectly they can block before meteor hits. Ultimately the problem with this skill is that the animation your character goes through to kneel down creates an extra second before you can breakout. It's about 1.5 seconds if you're in midair from a jump and 2 seconds if in mid dodge roll. This animation needs to be sped up or changed to not interfere with breakout mechanics.
#3 multiple consecutive ccs hitting you before breakout animation triggers.
I'm talking about getting hit with javelin then destructive touch then javelin and being juggled like this was mortal combat. This happens due to the delay in being hit with a cc vs the trigger of immunity. There's also a bug where if hit with a knock up and knock down ability simultaneously you slide around on the ground for about 15 seconds.
#4 is not as big of a problem as it once was but perma frost animation can delay breakout still.
It's an ultimate so this one is maybe justified.
I suspect some of these things may not be fixable, especially #3. 1 and 2 need attention above virtually anything else in pvp.
When adding skills in the future I'd like to see 3 questions asked :
1. Does this skill function how it was intended?
2. Is this skill at least somewhat balanced?
3. Does this skill promote fun gameplay?
If the answer to all 3 is no then redo the skill.
Let's look at timestop for a moment:
Ignores breakout
Is tool for zergs to clog doorways and can completely prevent healing when spammed by more then 3 people.
Requires players to spend entire pvp experience channeling one ability. Mandatory 2+ for ballgroups.
Lastly for a more functional game in pvp. QA need to test new cc abilities animations under multiple scenarios for breakout functionality before the skill is added.
Sorry for the wall of text everyone and thanks for reading.
If you believe this should be a priority focus as well, let zos know.