A way too many 2*, not a single 3*, that's the reason.
Sorry, but could you be a little more specific? Which 3* cards should I use?
I think it's a little top-heavy, and extremely weak against SoA. I also think clan synergy could be a little better. Have you considered a Montana half instead of Uppers? Something like Desmond, Donnie, Spiaghi and Mona would work really nicely. That gives you a second card that can bust through DR, a killer wall, a great Revenge card and a great DR instead of having to hope you draw Herman or Nellie.
If you want to shoot for the 100% KO more often, replace Neloe with C Wing, as well.
Montana pair, eh?
....Very well, but how about Edd Cr instead of Donnie?
Edd Cr is good, but he is very weak to DR. I personally like both, you can't go wrong with either.
Edd Cr and Donnie are both great. Which you want in this deck is a matter of personal preference, they both have great synergy with the Vortex bonus.