My guild forums say 15%. The question is probably far too advanced for beginner forums...
I was looking for these values as a way to theorycraft for building a BiS list for feral using the loot information provided by wowhead. In the process I figured everyone would be interested in these values so here it is.
•Melee hit/exp cap for level 90 Mists of Pandaria characters is 2550 (7.5%) for raid/level 93 bosses, 2040 (6%) for 5-man heroic/level 92 bosses. The PvP hit/exp cap is 3%, or 1020.
•Dual wield hit cap for level 90 Mists of Pandaria characters is 9180(27%) for raid/level 93 bosses, 8500. (25%) for 5-man heroic/level 92 bosses.
•Spell hit cap for level 90 Mists of Pandaria characters is 5100 (15%) for raid/level 93 bosses, 4080 (12%) for 5-man heroic/level 92 bosses.
•Racials: Draenei get a free 1% hit for all weapons. Certain races get a free 1% expertise for certain weapons.
•The whole odd Expertise/Expertise Rating thing is gone, it works just like Hit now.
•Pets fully inherit your hit/exp ratings and combine them to get their ratings. This means if you have 15% hit and 0% exp (warlocks), a melee pet will still be hit/exp capped.
Remember, these stats are before diminishing returns: See Theck if you want more DR math than your head can handle. The general TLDR idea for tanks is stack avoidance stats for best overall survivability but more RNG; stack offensive stats for more control over your active mitigation but slightly more total damage taken.
85 (1% Gain); 90 (1% Gain); Stat
265.08; 885; Dodge
265.08; 885; Parry
88.36; 295; Block
102.45; 340; Hit/Spell Hit
102.45; 340; Expertise
128.06; 425; Haste
179.28; 600; Crit
179.28; 600; Mastery (but varies for some specs)
322.58; 1259.52; Agility needed for 1% crit
648.91; 2533.66; Intellect needed for 1% crit
243.58; 951.15; Agility needed for 1% dodge (druids/monks), Strength needed for 1% parry (paladin/warrior/DK)
95.22; 310; PvP Resilience
N/A; 265; PvP Power (note: PvPP is half as effective for heals, so 530 for +1% healing done)
•Boss armor at 93: 24835
This is way more exciting than writing an in-depth description of why carbon is a !@#$%.