What I mean here is you have to have 40% crit unbuffed with your gear. Idk how great your gear is but in full BiS heroic loot you're almost 50% or something. Every plate class has a ton of crit. You also get 3% from
http://wotlk.openwow.com/spell=51473 and 15% for
http://wotlk.openwow.com/spell=59057 so that's 18% there and if you're at 40% crit let's say, then you get 5% from Feral alone much less agi or w/e else you get in raids. So now you're at 63% for Obliterate. Adding another 9% and getting to 72% with
http://wotlk.openwow.com/spell=49491 is not equalled to a flat DPS Boost from
http://wotlk.openwow.com/spell=49628. BCB is based on weapon damage, so the better the weapon the higher the damage. The more Armor Penn you have the harder it hits, the more Haste you have the more it scales and Haste at that point is worth more than Crit in general. Even w/o BCB Haste scales better with Armor Penn so this is free damage. Having extra crit when you're 60% is redundant.