Put simply: damage taken changed. Bosses in Battle for Azeroth don’t attack us quite the same way as bosses did in Legion. Before we get into the details of that, however, we should go over what exactly makes Mastery valuable, and why an effect that is unpredictable is able to be so powerful in practice for Brewmasters.
Mastery & Randomness
Our Mastery, Elusive Brawler, increases our dodge chance by X% (minimum: 8%) each time you could dodge an attack but don’t. This effect stacks, but your stacks go away when you successfully dodge an attack. Historically, this kind of random mitigation has been frowned upon: it doesn’t matter that a random effect is powerful on average if you die before it does anything. However, Brewmasters have a couple tricks that make this effect sing.
First and foremost: Mastery has built-in streak protection. If you have 20% Mastery, you are guaranteed to get hit by no more than 5 melees in a row. This number drops pretty quickly, too: 25% is 4 melees. 33% is 3 melees. That damage is still unpredictable and (due to Brew’s low armor) fairly spikey. Luckily, we have an additional tool to fix this.
Stagger once again rears its head. In this case, it is relatively benign and actually functions very similarly to its original purpose: it takes the edge off the damage. When we are hit, Stagger takes that inconsistent damage and smooths it out over a much more manageable 10+ second period. The combination of streak protection and natural smoothing turns our Mastery from an unpredictable-but-powerful effect into one that is both consistent and powerful—against a very narrow damage type.
Damage Has Evolved
In ye olden days, almost all tank damage was from auto-attacks. As a result, tank gearing was primarily about capping your Defense rating to prevented being critically hit. After that, you’d focus on getting as much of the defensive ratings (Dodge, Parry) as possible. It wasn’t until Cataclysm that damage began to shift towards so-called tankbuster abilities. Mists of Pandaria solidified this direction, and Warlords of Draenor eventually removed the old defensive ratings from gear in favor of other stats.
Following in Warlords’ footsteps, Legion had many varied tankbusters to draw examples from. Argus is perhaps most notable, as his Scythes dealt huge chunks of Physical damage. Although his autos also hit relatively hard, they’d almost never kill you on their own. Aggramar and Kil’jaeden were both skewed more towards melee attacks, but a heavy emphasis was still placed on tankbusters (the Foe Breaker portion of Taeshalach Technique and Fel Claws, respectively). Even Harjatan, though he lacked a tankbuster, had a unique damage profile with his large, persistent bleed Jagged that attacked tanks from a unique angle.
However, in late Legion the overall damage on almost every boss began to shift towards melee attacks. While threatening tankbusters continued to exist (all three of the above examples are from those later tiers), outside of Argus they began to comprise smaller and smaller parts of the tank’s concern—to the point that Protection Paladins were briefly all but eliminated from the tanking scene due to their weakness to high melee damage during Tomb of Sargeras.
This trend back toward autos has continued in BfA. Uldir held no real tankbusters besides Fetid Devourer’s Off-Tank hit (thrash). Mythrax ostensibly had a tankbuster in Essence Shear, but it dealt Shadow damage and only hit about as hard as a melee. In Battle of Dazar’alor, this trend has only gotten worse. Grong has a “tankbuster” (Smash) that doesn’t require cooldowns to deal with. Every other boss has a damage profile that consists of a mix of autos and some kind of small, constant magic or bleed effect.
Notably: our mitigation buttons don’t do much of anything against magic or bleeding effects, so Blizzard seems intent on tuning them low. They may force tank swaps, but are not dangerous if managed correctly. This, in turn, leaves us with exactly one source of damage to deal with: melees. On a fundamental level, this is the reason that Mastery went from just-another-stat to a powerhouse seemingly overnight. Even on bosses where the magic DoTs are threatening, such as Mythic Jaina, the melee (or Ice Shard) damage is simply so high that a narrow-but-powerful effect like Mastery reduces your healing requirement more than general-but-weaker effects like Versatility and Critical Strike.
Experimenting with Damage
In a nutshell: Mastery is disproportionately powerful right now because Melees are a disproportionately large source of incoming damage. This leads to an interesting question: what would damage profiles favoring Critical Strike or Versatility look like? Right off the bat, we know that the damage has to be undodgeable. If it could be dodged, then Mastery would continue to be the top stat. Beyond that, to answer this question we need to examine the differences between stats.
At a high level: Crit gives greater throughput but Versatility also improves our Effective HP. Celestial Fortune increases healing received by up to 65% of your Crit Chance, while Versatility reduces damage taken by 50% per percentage. Keep in mind that you die unless incoming healing (including CF) meets or surpasses incoming damage. However, higher throughput comes with a downside: Crit does nothing against one-shots. If getting killed before CF can heal you is a risk, then Versatility shoots up in value even though its average throughput may be lower.
Thus, to construct a damage profile that favors Crit we’d build a boss with heavy, consistent damage that can’t be dodged. Something like Harjatan, where there was a large, unavoidable bleed that kept you low enough that CF didn’t do too much overhealing. On the other hand, to build a boss with Versatility favored we’d need frequent, unavoidable nukes that could legitimately kill us. Given Stagger’s strength against physical nukes, these would likely need to be magic damage and would need to occur more often than we had cooldowns to cover.
Throughout this, I haven’t mentioned Haste—and it isn’t just because haste is bad. Haste is simply hard to evaluate. It performs exactly one function defensively: it gives us more Brews. However, each additional Purifying Brew has the potential to reduce the value of other brews, depending on when exactly it is available. From a raw throughput perspective, Haste is fine. However, there is no universal fight where it is best. Something like Fetid Devourer is the closest we’re likely to get to an encounter where Haste is BiS, but that fight allowed you to out-play the surface-level Haste requirement.
The damage patterns for Crit and Vers are—unfortunately—unappealing when combined with BfA’s tank design. Almost all mitigation buttons only affect non-bleeding physical damage, so frequent magic nukes or large DoTs are likely to play out as healer mechanics more-so than tank mechanics. However, this example does highlight a central piece of the puzzle: Stagger.
As long as we have such high Stagger, physical damage can’t put us in the realm of a one-shot unless it absolutely annihilates other tanks (see also: Argus). As a result, most of our gearing decisions as Brewmasters are going to boil down to “how can I minimize my average healing requirement?” Our damage is already smooth, our health is stable. What we need is throughput, which Mastery is excellent at delivering.
Is This a Problem?
In my eyes, this is more a curiosity than a problem. Even though Mastery is better than Critical Strike or Versatility for raw throughput, it isn’t an overwhelming gap. Mastery tends to come in at 30-50% better per-point than Crit or Vers. This is enough to make decisions on side-grades clear, but not so much that we’d ever equip a lower-level piece just to get more Mastery—in no small part a result of Armor and Agility’s collective contribution.
The bigger issue is that so many fights feature the same damage profile, which has several downstream effects on gameplay. First: it means that our gearing choices are one-and-done. We don’t need to interact with gear after equipping it, and never really need to hold onto gear because the stats might be better for a later boss. When it all has the same damage profile, we simply don’t touch our gear.
The Bigger Problem
More problematically: disproportionate melee damage results in stale gameplay. Not only is every fight similar—possibly leading to tank players getting bored after they’ve mastered mitigation of melees—but as a direct result the same specs are going to be best at dealing with them. There are no fights in BoD where you take a Blood DK because Death Strike is really good at dealing with their damage, or where you take a Vengeance DH because the damage comes in bursts that line up well with Demon Spikes.
While every spec is playable in Mythic raids to various degrees (I will again note the BDK/VDH comp the other team in my guild killed M Jaina with), the same-ness of fights exacerbates balance issues. You only choose to take a tank that isn’t a Brewmaster or Warrior because you need specific tools like Death Grip, Blessing of Spellwarding, or Stampeding Roar. The balance is not so far out of line that you can’t kill these bosses with those specs. After all, plenty of people killed Jaina and G’huun well before me without playing Brewmaster—but when you’re given the choice, why take the weaker option? And if you’re going to be a one-trick-pony, why not pick the one that best answers the singular damage profile of Battle for Azeroth’s raids?
Looking Forward: Mastery in 8.2
Things are a little better in Eternal Palace. While there is only one un-dodgeable, high-damage tankbuster, this is a step up over 0. It happens to be on the first boss and is intended to be split between raid members, but I’ll take wins where I can get them. Yet another fight messes with the old stacking-melee-amplifying-debuff formula, encouraging you to front-load your cooldownrs rather than using them to deal with high stacks. In general, the bosses in this tier have more interesting tank-mechanic designs. Personally, I hope this indicates that we’ll see more varied damage profiles in the future that encourage us to think about our gearing decisions more often. We aren’t there yet, though, so Mastery will continue to be our best stat in the coming tier.