Physical mitigation change intentional?

So, after seeming to take increased damage in ICC this week, and various other reports confirming others felt the same, an intrepid guild member and I decided to confirm once and for all what the current active mitigation formula is. The old formula was:

Reduction = Armor / (Armor + MobLevel * 467.5 - 22167.5)

The new formula for Cata bosses is:

Reduction = Armor / (Armor + MobLevel * 2167.5 - 158167.5)

The trick is confirming this. It turns out, the first boss of Forge of Souls performs an ability called Magic's Bane which is fixed physical damage:

http://www.wowhead.com/spell=69050

Basically 5500 physical plus half your mana as damage, capping at 15,000.

To test this, my feral guild mate strapped on his DPS gear (to avoid armor procs), I grabbed my priest, and we went into the instance. During the fight, the boss performed this ability twice on me (Disc Priest, armor of 11,130) and twice on him (Feral in bear form, armor of 27,971). Since he has no mana, he would take 5,500 damage, and I would take the full 15,000, both of which are entirely physical.

The two hits I took:

10/16 17:30:17.969 SPELL_DAMAGE,0xF1308E910003BBD1,"Bronjahm",0xa48,0x0100000003AEF176,"Avalena",0x511,69050,"Magic's Bane",0x1,937,-1,1,0,0,8625,nil,nil,nil
10/16 17:30:34.796 SPELL_DAMAGE,0xF1308E910003BBD1,"Bronjahm",0x10a48,0x0100000003AEF176,"Avalena",0x511,69050,"Magic's Bane",0x1,8168,-1,1,0,0,1394,nil,nil,nil

His hits:

10/16 17:30:17.969 SPELL_MISSED,0xF1308E910003BBD1,"Bronjahm",0xa48,0x01000000006AA749,"Kaetzchen",0x512,69050,"Magic's Bane",0x1,ABSORB,1993
10/16 17:30:34.796 SPELL_MISSED,0xF1308E910003BBD1,"Bronjahm",0x10a48,0x01000000006AA749,"Kaetzchen",0x512,69050,"Magic's Bane",0x1,ABSORB,1992

So I took 9562 both times, and he took 1992 and 1993.

Using the new formula, my reduction percent is 11130 / (11130 + 82 * 2167.5 - 158167.5) = 36.26 percent, so the damage I take would be 0.6374 * 15000 = 9561.4. Consistent with the new formula (the old formula would yield 8840 damage).

For him, you must also take into account the innate 12% damage reduction of a feral tank:

27971 / (27971 + 82 * 2167.5 - 158167.5) = 0.5884

So his reduction would be (1 - 0.12) * (1 - 0.5884) = 0.3622, yielding damage from a 5500 attack of 1992 -- also consistent with the logs.

So, this pretty much proves we are using the new scaling of armor on ICC bosses, and yet we've had quite a bit of reduced mitigation thanks to the reduction of base armor as well as having tank gear getting less stamina at a given ilvl than dps gear.

The result of the changes in these formulas are that a tank with 32,000 armor would have 59.95% reduction against a lvl 83 boss instead of the 65.80% we had before; this means tanks are innately taking 18.25% more damage. That's quite a bit.

It is hard to believe this is intentional; combine with most plate tanks losing upwards of 4,000 armor, and Demoralizing Shout (and related abilities) reducing damage by less than before... this is a lot more incoming damage. With more avoidance, this means tank health is spikier than ever!

Can we get confirmation this is intended, or is it a bug? If the latter, it would be awesome to get it fixed; for guilds still learning HLK or HRS, this is a lot of damage.

Thanks,
Valen