I'm close to Battlemaster except for 100 wins in 3 battlegrounds (and I'm over 85 in each of those 3) and Frostwolf Perfection.
I completed Alterac Blitz ages ago and I've seen it happen in battlegrounds since Cata 3 or 4 times in my 150+ AV matches since then.
I've never seen a team come even close to Frostwolf Perfection.
An achievement that requires 40 people to cooperate should not exist unless there's a way to queue 40 people. (And I'm not talking about using an add-on to do it.)