It comes down to the following, and injuries expose all of the below:
1. Rebuilding. Yep, we're in year 2 of rebuilding. As much as people don't want to admit it, this is true. When you are rebuilding, you lack depth because you are basically starting from near zero. The Bills had precious little to build on, and when those building blocks went down, we got screwed. Drafting Spiller at what was a position of strength didn't help much, but I think Nix realizes his mistake.
2. Bad drafts for 10 years. Also contributes to #1, but there's no way Buffalo can recover quickly from years of poor drafting. You can't trade away #1 picks (for bledsoe) and whiff on multiple #1 picks (Williams, McCargo, Losman, etc.) and recover in two years. It doesn't happen. Sorry to break it to everyone, but it doesn't happen.
3. Getting rid of good players. This is partially due to the revolving door at Head Coach, but look at the good players that the Bills get rid of or lose because they are constantly starting at year 1 of rebuilding. Greer, Fletcher, Schoebel, Leonhard, Trent Edwards (just kidding!), etc. A lack of consistency in the FO and at HC leads to this issue. And now people want to get rid of gailey and nix before the fruit is even ripe. Idiots don't realize that inconsistency is part of the problem.
So when we have so few good players, and they all get injured, you see an absolute joke on the field. No coach can deal with that, although I think Edwards could do better and he needs to GTFO.
So going from 32 to 25 is a substantial improvement.
Quiz: what does new england and GB have that most teams in the NFL don't? A HOF QB, silly, and consistency in the FO.