I indeed had minus DKP in some instances due to the fact that I took loot that no one else wanted (Dragonfang Blade, The Untamed Blade for example) of which I thought it would be a shame to be disenchanted. And since I didn't need anything from those instances anyway, I thought it was a shame to let them be disenchanted, since we didn't use the nexus anyway - and I could find some use of them.
But then again, if you check, for example, Naxxramas DKP I was number 1 on the list.
Anyway, if you have any problem with me leaving feel free to contact me ingame.
