On-use avoidance trinket; what benefit are we looking at?

I've been pondering a few things regarding on-use trinkets recently, and I'm uncertain about their usefulness beyond the magical 102.4%. Additionally, I'm uncertain how the RNG works w/r to when a parry, a dodge, or a block takes place.

Let's assume that I, fully raid buffed, sit at exactly 102.4% CTC. I equip a stam trinket of choice, alongside Fire of the Deep (458 mastery, on-use 2290 dodge for 15 seconds, 1:30 cooldown). I understand that once I pop my trinket, the "flat mastery" equivalent of the 2290 dodge gets shoved out of the picture, and is essentially "wasted" for the duration of the effect, how does the game practically and technically deal with this? Will any block in that bit of my avoidance turn into a full dodge, or what?

One of the reasons I'm curious about this is the trinket choices I've been using on Baleroc HC for our farm nights recently. I use the Moonwell Phial (to dodge Decimation Blades), and the Mirror of Broken Images (to mitigate the fire damage from his Inferno Blades more effectively and smoothly), but I have to wonder how any additional avoidance supercedes standard mitigation/block when 102.4% CTC is reached.

Hope this wasn't too difficult to understand; it's a little hard to put my concern in words - thanks in advance.

If understand your question, I think the answer is as follows. Say the Fire of the Deep trinket gives you 8% dodge on use. That means, given you were CTC capped anyway, pressing the on-use button would increase your chance to dodge by 8% and reduce your chance to block by 8%. So yes, in 8 out of a 100 cases, strikes that would merely have been reduced (blocked) should be fully avoided. It seems a reasonably substantial on-use benefit to me, given that gearing in WoW we tend to deal with rather small marginal changes.

econ21 wrote:gearing in WoW we tend to deal with rather small marginal changes.

Very true, but to be fair, I think a stamina trinket would present a more worthy addition to your gearing if you're at the ctc cap, given the amount of heavy magical burst or otherwise unaviodable damage in most of the DS raid encounters (and burst damage is the #1 source of tank death...besides afk healers).

Solare wrote:

econ21 wrote:gearing in WoW we tend to deal with rather small marginal changes.

Very true, but to be fair, I think a stamina trinket would present a more worthy addition to your gearing if you're at the ctc cap, given the amount of heavy magical burst or otherwise unaviodable damage in most of the DS raid encounters (and burst damage is the #1 source of tank death...besides afk healers).

Fair point, but even a lot of stam trinkets either have an avoidance or mitigation proc of sorts.

The tank trinkets are pretty meh these days (and have been for a while, I feel)...

I'm probably going to go with a combo of Fire of the Deep and Indomitable Pride, possibly upgrade to two stamina trinkets later in the patch.

If it ever drops, I'm going to run Indomitable Pride and Mirror of Tol Barad as my default setup.