Korrak’s Revenge is a meaningful name: if you went to kill him, you will have lost the BG regardless of side.
That said, the reason for the situation is different.
Firstly, alliance queues are a few minutes; horde a quarter and up.
Second, just being inside is granting ridiculous passive XP, and even more if you have even one of the BG XP trinkets.
As a result… to level most efficiently as alliance, you should go in using your fast queue, and then loose as fast as possible to requeue. Time-wise, swallowing losses (and halved BG-end XP bonus) is most effective if you account for shorter queue. As horde, the most effective choice is to just push ahead - blow up 2 bunkers and cap 2 graveyards on the shortest route, then zerg the alliance leader.
That’s all there is to it.
And the fact that even on last day you could grab the main quest, then go to Amphitheater of Anguish in WotLK era zone Zul’Drak, and either do the Amphitheater quest line (which summons… Korrak) or just party with someone who hasn’t done that quest line, and get the quest to kill Korrak to complete, didn’t help. Korrak was clearly there to add some chaos and agenda… but the thing in Zul’Drak circumvented that, both sides just complete the quest outside of the BG and then just ignore him and level most efficiently. It doesn’t help that the BG version of Korrak is a beast that you just can’t beat without a full healer-tank-deeps triad there, while the Zul’Drak one is a leveling group quest mob - a walkover, particularly for toons well over 80.
At start, the quests to hand in wolves, rams, mine resources etc. worked as they did ages ago, but then they changed it to a daily quest, so people stopped… both going to the mine, and farming wolves/rams, not to mention armor scraps.
And the big summons… aren’t effective when compared to afking in base or zerging.
That is why many alliance players passively cooperate with horde, even without the need to communicate or coordinate outside, say via Discord or some such.
When the event started, I did have one BG that lasted like 1,5 hours, we summoned an Ice Lord and had an honest battle - heck, both sides assaulted Korrak and he was killed. But… that was before Zul’Drak trick was known, and before farming resources was nerfed. Was good while it lasted.