that was because ANYONE who played wow and did al'akir heroic knows 10man was so so so much easier than 25 heroic, due to the room, 10mans had all the room in the world while 25mans had none and the damage was much worse.
paragons kill actually involved 17 manning phase 1 while 8 stayed out, so 25man was so much harder they couldnt even use 1/3rd of their raid.
any person who follows wow world firsts knows why 25man was seen as the true world first for al'akir since its difficulty was was beyond that of 10man.
personally my guild couldnt get past 40% of al'akir 25 hc, 10man hc we kill him in 20 tries 1 night.....25 man had to wait till we had firelands heroic gear.