It works the same for plate tanks, but it's not as effective as on a druid tank. Plus we have parry as well as dodge, and block (when you carry a shield).
Druid Armor is roughly equivalent to a Plate tank using Bonus Armor pieces.
The Plate tank has Dodge, Parry and Defense for avoidance
Druids have Dodge (and much less Defense) for avoidance.
Plate tanks typically have higher avoidance, while bears typically have higher health.
Against a single boss, a Druid will proc Savage Defense based on their Crit chance (40-50% in bear) t o absorb the next hit for 1500-2500 (based on Attack Power)
A Warrior or Paladin will either Block More often, or for more, depending on which class is in question. It should roughly equal out against a single boss.
Druids using Shifting Gems is fairly common for red slots. AGI effects Crit Chance (for Savage Defense) Armor, and Dodge. Druids do not gem for Dodge Rating, because AGI is tons better to socket for.
Let's say for sake of argument Festergut hits you for 25,000. If you lost 5% mitigation that suddenly becomes 26,250. If you lost 4-5k Hitpoints you are now not only getting hit harder, but can take fewer hits.
Originally Posted by psychocrasha
The argument of if that gains you 3% avoidance is moot because flat out you can't rely on 3%. You could take every single attack during the 30 seconds you are tanking at 3 inhales. It's random for a reason, and you gaining 3%-5% is not likely to save you because as soon as you take several back to back hits it's going to be all over since each individual hit will be hitting for more and you have less of a buffer from 100% to dead.
Quite simply, your healers are thinking wrong.
Example: Last time i tanked fester25, i had 60.8K raidbuffed. I got hit for around 28K. That means i can eat two full blows and survive it. And it happened. I remember coming back up from 200 hp left (thank you blood draining enchant, i love you). Now consider the same scenario. Say i had 5% more avoidance at a cost of 2K hp. We'd have wiped. Simple as. For exactly this reason i equip two stam trinkets instead of one stam one armor trinket. On other fights i usually go with the armor trinket but for fester, especially fester25, it's stam all the way.
Your healers are insisting on not getting the point. Take the cost of a wipe and put the bear on the 3rd inhale.
Unless your healers start changing your attitude, like Shortypop said, you're going to run into way worse issues on future bosses. Mainly Sindragosa comes to mind (mostly magic damage where all that lovely avoidance does crap all - oh and the melee damage isnt trivial either)
As for glyphs etc. For specifically festergut, yeah, the shieldwall & last stand glyph really arent necessary. But if you think longterm and dont really want to switch out glyphs during a run, i've found Shield Wall, Last Stand and Taunt glyphs to be the ones to use. Why? Shield Wall & Last Stand glyphs put warrior cooldowns on an equal time basis with other tank cooldowns, meaning you can rotate them just as often as other tank classes. Skip on them and you'll really end up being the worse option on fights that require frequent cooldown usage. I still carry a bunch of glyphs in my bags to change out as necessary.
Hitrating yes, it's not that important. Due to the double benefit (dodge AND parry elimination) expertise does give better returns than hit till the dodge cap, same return as hit after dodge cap. The problem is, if your hit drops too low, you'll start missing taunts too often, even with a taunt glyph. On our last Sindragosa fight, i went in with some frost resist gear that dropped my hitrating to 86 and i had 4 taunts miss in a row. Next try i switched around some gear, ended up with 120 hitrating and never missed a taunt. You CAN survive with low hit but on fights where proper taunting is absolutely necessary, i prefer my chances a little higher.
As for avoidance gear. I sort of collect some on the side. The bonus armor pieces are EH pieces so i fill those out with pure stam gems. For any extra gear that happens to come my way, i gem for the socket colors, getting in some more avoidance, in case where avoidance turns out to be better. And you know what? every single piece i gathered for my avoidance set is sitting in my bank, collecting dust. If healers cant keep you and the raid up in EH gear, then they're just not equipped to handle the encounter. And if they can, then they really wont notice the 5% avoidance difference at all anyway.