This. Counting casualties the Horde is the clear victor after the whole War of Thorns thing.
The Alliance lost Teldrassil along with a load of civilians. The Night Elf race is nearing extinction. It didn't cost the Horde that many casualties to get that done. Clear victory for the Horde here.
Battle for Lordaeron is a pyrrhic victory for the Alliance. Yes, they won the battle. But at what cost? Lots of casualties trying to siege the city and claim it, only to rend it useless due to the blight. And meanwhile the Horde evacuated most people.
Add these two together and the Alliance is really losing in terms of casualties.