Tank Metrics

What should a tank look at as a simple metric on a combat log?  Damagers have DPS, healers have HPS, tanks have… what?

Our logs will give you three easy numbers, and this post described how useful they might be.

Damage Taken

Total damage taken seems like a natural way to compare or rank a tank.  Unfortunately it doesn’t work so well for a variety of reasons:

  • Most fights require tank swapping or different jobs for each tank, which can lead to big differences in total damage taken.
  • Some tank classes just take more damage by design.

So while not a useless number… it isn’t all that helpful either.

TMI

This is a metric created by some theorycrafters, and you can read full detail about it here.

TMI was created primarily as a theoretical metric to be used in simulation and mathematical modeling to help determine the relative value of different stats on gear.  We use TMI and simc to help us create our tanking stat weights on AMR and find it to be very cool and useful.

We calculate it on combat logs… but it is of pretty limited value on logs.  In theory it should tell you how spiky your damage is — do healers see your health bouncing all over the place and go into panic mode, or is it steady and predictable?  Good concept and metric, but the numbers you see on combat logs don’t translate into actionable information usually.

At lower difficulties where the damage spikes just aren’t that dangerous (basically anything below Mythic), the metric can be skewed and give a number that is hard to interpret.  Even at Mythic difficulty, you only really want to use the number as a relative comparison of tanks on the same fight and probably of the same class.  You don’t want to use TMI as an absolute metric where value X is “good” and value Y is “bad”.

New!  Healing Required / Second

We have created a new metric with our latest log update. We just call it “healing required per second.” It’s THIS easy: when a tank is “main” tanking a boss, how much healing does he require outside of what he can do on himself?

This is NOT a one-size-fits all algorithm, trying to smush each fight into a metric. We code each boss individually so you are only looking at what’s important for tanks in each fight. Every boss is customized 🙂

This metric is live for NEW logs. Go to the Damage Taken report to see it. If you want to test it out with a log you’ve already uploaded, you can change the file name and upload it again. NOTE: It will show duplicate logs if you do this though.

HRPS

How it’s Calculated:

  1. For each boss encounter, we define what constitutes “main” tanking.  The goal isn’t to necessarily capture every point in a fight where a tank is taking damage, but instead to define the “main” and more consistent parts.  For example, on The Butcher both tanks are considered “main tanking” for the entire fight.  On Mar’gok, a tank is only considered “main tanking” when Mar’gok is hitting them.  A tank will certainly take damage from the different adds in the intermission phases of Mar’gok, but it is highly variable depending on which adds and what kind of strategy your team uses.  So we cut it out for the purposes of this metric.
  2. For the time where a tank is “main” tanking, we total up how much damage they took, and subtract self-healing and self-absorbs.
  3. What you are left with is how much healing your healers would have to do to keep the tank alive during the more consistent tank damage phases of each fight.

This metric does not tell the whole story of course, just as HPS does not tell the whole story for healers.  But we think that it is far more useful than total damage taken and for more practical than TMI when looking at a log.

Here are a few potential uses for this metric (assuming it works out over the next couple weeks, we’ll be keeping an eye on the log data):

  • Rankings.  We think this number is a decent candidate for tank rankings and percentiles.
  • Actionable Benchmark.  A damager can look at DPS on a fight and try to improve it the next time he does the fight.  We think this number can function similarly for a tank: try to reduce it each time she does the fight.  In general a tank who uses active mitigation and times cooldowns will take a lot less damage during these main tank phases.
  • Adjust Tank Assignments.  If you notice that one of your tanks is requiring a lot more healing than another on a fight, but they are of equal gear and skill… it is a good indicator that maybe your strategy for the fight is off.  Maybe a more even tank swap would result in a better damage split?  Depends on the fight.

Want to see a log of it in action? Any log uploaded in the past 2 weeks shows it. And here’s an example from our raid’s mar’gok’s attempts last night: http://www.askmrrobot.com/wow/combatlog/3d037a7d-e380-4430-b905-ad78db6dd5cd/report/12#v=0,d=2

18 Comments

  1. Eeeeeeexcellent *steeples fingers*

  2. The healing required per second feature doesn’t seem to be working correctly for Twin Ogron. My log at http://www.askmrrobot.com/wow/combatlog/fff22311-042e-4c2f-b095-965c216a106b/report/53#v=0,d=2 does not have a value for healing required per second for the warrior tank Doogru. I don’t know if this is because I’m using Gladiator as my lvl 100 talent (for the damage reduction) thus causing Mr. Robot to identify me as a dps rather than a tank, though that’s my suspicion.

    Other than that minor issue, great work as usual Mr. Robot (and team)! Cheers!

    • Thanks for posting. In some cases, tanks weren’t meeting criteria, because the criteria was too strict. In an update today, we should have that fixed. It won’t be retroactive though.

      You CAN upload the log again if you rename the file, but be warned: you will have duplicate logs for you and everyone in the raid.

      • Unfortunately it appears our favorite robot still isn’t working for me, though this time it’s on mythic Brackenspore. You can see the log here http://www.askmrrobot.com/wow/combatlog/48fcac5b-dc93-4efe-bc50-ba56c1a4cc1a/report/2#v=0,d=2

        • Your poor warrior. We’ll take a look into this, thanks for posting!

          • Heya Zoop & gang, as a tank who’s killed Mythic Brackenspore, I’d like to pitch in: the boss hits like a girl (no offense to you and your gals!) – the add is who will rock your world at 5-6 stacks+. Even Bracken’s breath is a joke compared to how hard that add hits at higher stacks.

            I would suggest perhaps taking that into account on that fight on Mythic.

            Additionally, we found that the 3 tank strat left a lot to desire – you’re largely bringing 3 tanks to eliminate the 3-4 rot stacks on your add tank. Rot didn’t feel like it was sufficiently painful to warrant bringing a 3rd tank over a 5th healer or another DPS.

          • Davinc, thanks, that’s actually helpful. Now that our big combat infographics are out, we have time to refine some of the HRPS for the fights. Also, if you’d like to give any feedback on how we handle it in BRF as you progress, I’d love that 🙂

        • Did you only tank adds and never brackenspore by chance? The metric is hard coded to only look at main tanking events, which in this fight is only brackenspore while actively melee swinging or breathing necrotic breath (the infesting spore phase doesn’t count).

          Also, if you tank the boss for <10 seconds, we don't count it (assume someone accidentally pulled aggro).

          • I guess that’s what happened then. In our mythic strategy, I’m always tanking the big add while the other two tanks are alternating “main tanking” Brackenspore. Thanks for the quick feedback!

  3. The healing required per second feature doesn’t seem to be working correctly for Twin Ogron. My log at http://www.askmrrobot.com/wow/combatlog/fff22311-042e-4c2f-b095-965c216a106b/report/53#v=0,d=2 does not have a value for healing required per second for the warrior tank Doogru. I don’t know if this is because I’m using Gladiator as my lvl 100 talent (for the damage reduction) thus causing Mr. Robot to identify me as a dps rather than a tank, though that’s my suspicion.

    Other than that minor issue, great work as usual Mr. Robot (and team)! Cheers!

  4. How do you handle Protection paladin Shining protector heals? are those considered selfheals or not for the purpose of HRpS?

  5. Perhaps Cooldown Usage?

    When Boss does X ability is the tank using active mitigation properly?

    I think a great tank is one that does everything he/she can to actively mitigate spike damage coming from a boss’s ability.

    -D

  6. Is it possible to calculate the expected total damage taken per second prior to blocks/absorbs/parries/misses etc? My understanding is that this is one of the primary inputs to resolve. If it is possible to isolate that part of resolve, or otherwise calculate an expected damage per second, then taking that number and subtracting your external healing required per second should give you the total amount of damage that a tank “mitigated” or healed or otherwise handled. This is a number I would very much like to see.

  7. I don’t think this metric is working to well for normal or heroic raiders as a ranking method. Flex scaling seems to play too big a role in these cases. Tanking larger raids makes you look worse, and tanking 10 mans makes you seem better. For Mythic this is obviously not a concern.

  8. Does the healing required per second account for tank self-healing? In other words, if I required 15k hps on a boss, and did 8k hps to myself, did I require only 7k hps from other players, or did I take 23k dps and my self healing brought my hrps down to 15k?

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