Collectively, how about the Atlanta and San Diego offenses? You can basically include every single player from those teams in the disappoinment category. You have to think the main names there will still turn it around, but if they don't - you'll have a handful of busts from each team.
I think with Atlanta you cannot include Turner or TGonz. Both are having decent years and Turner has been very consistent to this point. San Diego you could say Rivers but VJAX and Gates have both been injured.
Mendy is high on my list. He has had only one good game thus far...