There's been some discussion on forums about how mitigation values seem to be out of line in tier 8, with the Ruins of Kunark expansion. This is based on several factors. The raw mitigation numbers seem unimpressive to some in comparison with dropped items. And the mitigation of the brawlers, who wear leather, doesn't seem to be able to keep them from getting oneshotted.
I've also heard from players in game that mobs in RoK seem to be hitting less often, but harder. And a third thread of this is that the word on the street is that the high end raiders have seriously hit diminishing returns on mitigation, so that plate tanks are now seeking more avoidance. As a side note, with all the adornments available, as well as dropped and quested items, and AA abilities, the plate tanks can build up very good avoidance. Which is making the brawlers a little jealous, I'm afraid.
I decided to gather some data. I have collected the mitigation values on mastercrafted armor from tiers 2 to 8 and put them in a spread sheet. I have confirmed that the ratios for plate-chain-leather have remained consistent, and I
calculated the plate mitigation value divided by its tier.
I didn't use fabled raid gear, it's much easier to get consistent data on mastercrafted gear. However, I think this will be a good indicator, since game developers have stated they use a program to determine mitigation values, so we're dealing with some kind of formula. Hence, we want to study the trends of that formula.
I also plotted this stuff on a graph:
There are two-major takeaways from this. Mitigation, in general, is on a nearly-linear growth curve. However, there is small flattening of that mitigation growth for tier 8. Mit/tier grew slightly all the way through tier 7, and now it's dropped off a bit. Why? I couldn't tell you. But it's definitely there, folks aren't imagining it.
And mobs are hitting harder, it seems. It's harder to gather data for this, since monsters are all different, after all. One kind of mob isn't supposed to hit exactly 8/7ths harder than another one, and there is a lot of variability in how hard they hit, too.
I haven't seen a formula for mitigation diminishing returns, but I assume that it's linear with level as well. Which would tend to put the squeeze on tanks a bit more. Was this the intent of SOE? I don't know. Maybe there's a single mitigation/avoidance sweet spot, which is reachable only via raid buffing, and both bruisers and plate tanks can get to it? I don't know.
But player DPS has undergone enormous growth in this expansion, more than linear by quite a lot, I'd think. They might think that they need to do something to help the mobs out.