Nurgle is not outstanding because they are not good in shooting, mobility, or assault which is where other factions shine. But you can come up with some creative lists and I have something I can't wait to try.
It is true, tarpitting can only get you so far. I do however hope they do beasts of nurgle justice (and give them some new plastic models! I have seen some new leaked artwork that I suspect has some beasts of nurgle in it) because they are an under appreciated unit. Attention Seeker has won me some games from unsuspecting foes.