First things first, a little bit of background is in order. I am currently a tank for a 10 man raiding guild and was a DPS for a fairly hardcore 25 man guild back in Wrath. I did some off tanking in WotLK for alt raids, heroics, etc. I stopped playing WoW about halfway through ICC and came back during MoP with the ToES raid content and have been a tank all through Mists. The release of new content in Siege of Orgrimmar got me thinking about the life of a tank during this expansion and how different it is compared to prior expansions. The main point I would like to bring up for discussion is the emergence of forced tank swapping mechanics as a pervasive and nearly core element to MoP raid encounters.
I will focus on Wrath and Mists content as I did not participate in Vanilla, BC, nor Cata. Additionally, as I understand it, the differences in the game are perhaps too wide to really make a comparison reaching back farther than Wrath content. I will summarize each instance and provide some numbers for easier comparison. Specifically, I am looking at forced tank switching based on debuffs.
--15 boss encounters with 1 (Gluth) requiring a tank swap.
Naxxramas was a really well designed instance and perhaps this is partly due in part to its Vanilla origins. The options people had in terms of wing progression and the variety of mechanics made for a lot of fun. Thinking back on this content I have fond memories of fights like Thaddius, Four Horsemen, Sapphiron, Kel'thuzad, the list goes on. Granted, a lot of the fights were very difficult but that doesnt mean they werent well designed or fun.
One point of criticism is that most of the fights required following the traditional main tank on boss with an off-tank on adds format. Some of the fights only needed one tank, thus requiring either rotating personnel or forcing the tank(s) to build two sets of gear, probably at the detriment to a DPS member of the group.
--14 boss encounters with 6 (Flame Lev, Razorscale, Kologarn, Thorim, Hodir, Algalon) requiring a tank swap.
Ulduar is by far my personal favorite raid instance; this is when I came into my own as a core raider with a serious heroic guild and I acknowledge that this experience colors my perspective to a certain degree. That said, we see a significant increase in the use of force tank swap mechanics, perhaps this was an internal design team decision to get more tanks involved. On fights without swapping mechanics the off-tanks were generally following the same add management duty as prior content. I dont personally remember my guild's off-tank(s) ever complaining about their job, but I imagine it could have been somewhat boring to always be stuck on add duty.
Trial of the Crusader:
--5 boss encounter with no tank swap mechanics (almost).
Many regard ToC to be a complete failure. I had no real problem with it and thought it made sense in a larger story context. I also really enjoyed the challenge posed by Anub'arak. This raid only has one instance of tank swapping and it is on one of the three beasts that comprise the first encounter. Gormok applied a bleed dot to the tank and required a swap until your raid was geared enough to just power through it.
Ice Crown Citadel:
--12 bosses with 5 (Deathwhisper, Saufang, Festergut, Putricide, Arthas) requiring a tank swap.
ICC was another excellent raid and I am sad that I had to stop playing before I could finish it while it was current content. Again, we see more use of tank swapping mechanics but they are not strictly forced by debuffs. For example, Festergut just put out so much damage based on his mechanics that tank swapping with cooldown rotation was sometimes necessary (depending on healer and tank setups). I cannot remember if some of these swapping mechanics became trivial with gear.
Wrath had 46 encounters with 12 including a forced tank swap mechanic. This come out to 26% of bosses utilizing this design method.
Moving on to Mists of Pandaria we see a dramatic change in the number of bosses using these mechanics. I am interested to see if the Cata raids bridge the gap between WotLK and MoP and may look into those encounters, but I wanted to start with the two expansions I was familiar with. If someone would like to contribute based on their experiences in Cata, that would be helpful.
--6 bosses with 3 (Stone Guard, Geng, Gara'jal) requiring a tank swap.
MSV was split half and half for swapping mechanics. I did enjoy the different nature of the Stone Guard's swap mechanic. Rather than simply having a debuff applied to the tanks you had to manage a boss resource mechanic and ensure they were in the right place at the right time; I thought it was fun. Feng kicks in with the stacking debuff and Gara'jal forces a swap with the spirit world stuff (similar to Algalon).
...Part 2 follows below...