In late August, Theckhd of Maintankadin started an epic post to work out, if expertise was an avoidance stat, how good would it be? The exact ratios below apply to paladins, but the principles can be applied to warriors and DKs too. I’m not sure it works for druids because they’re so dodge-oriented in the first place.
Update Feb 9th 2010: most bosses in Icecrown do not parry-haste, so expertise is just a threat-stat in that perspective. Read more.
Update Jan 16, 2010: Theckhd’s completed further analysis, and graciously considered death knights too. Key finding: DKs gain the least avoidance from expertise of all the tanks:
For Icecrown Citadel,
- For Paladins, expertise is roughly 91% as effective as dodge rating for reducing incoming damage, assuming a boss swing speed of 1.4 seconds (after JotJ). It varies significantly with boss attack speed though, from 78% @ 1.2 to 154% @ 2.4 speed.
- For Warriors, this range narrows to 52-102%, with an “average” of 60% at 1.4-speed.
- For Druids, it’s 49-98%, with an “average” of 60%
- For Death Knights, the range becomes 36-71%, with an “average” of 46%.
For bosses outside of Icecrown, we would use an average swing speed of around 2.0, giving average values of 87% for paladins (53%-104% range), 57% for warriors (30%-69%), 56% for druids (28%-68%), and 29%-45% for Death Knights (28%-52%).
The below original post is for Paladins, not DKs.
His original conclusions for Paladins were:
- Expertise is about 73% as effective as dodge rating for reducing incoming damage.
- Expertise is about 69% as effective as dodge rating for reducing the number of incoming attacks that connect.
- Expertise is actually 2x-4x better than dodge at reducing spike damage intake from boss melee attacks, with the added benefit that it preferentially reduces the largest spikes, thus smoothing out our spike damage by reducing the maximum spike size.
- Paladins also get: each point of expertise rating also gives us about 1/3 of a point of STR.
The significance for gear decisions: if you were comparing armour with expertise to that with dodge, that there’s more equivalence than you might have thought. It’s not like the expertise-gear is a net avoidance downgrade, in real terms, even though TankPoints won’t show its value in your avoidance total.
Expertise is such a great stat. Don’t worry about going over 6.5%, enjoy it.
TankTotals can calculate the benefit of expertise in its time-to-live value (not sure which math Reynard is using though, I asked in comments).
Further reading if you want more stats? Theckhd also analysed agility compared to dodge, and found them to be fairly close too. Check this baby too, whoa yeah maths porn. Lastly, why avoidance is good at high levels.
My thanks to Sproutster on TankSpot for sharing the original post.