Buts its not even like they made Dream Team moves. They signed one good, albeit injury prone player, and a journeyman who played in sub packages and got some sacks while struggling with the rest of his game to now play every down.
Their defense was bad last year. Williams figures to make it better, but I don't see better parts surrounding him in Buffalo than I saw all those years in Houston, when they averaged a 24th ranking in points allowed and were never in the top half of the league.
When I read stuff like this from a supposedly intelligent football fan, I just have to shake my head because it's clear you haven't really looked at the Bills at all or given them a fair evaluation.
First, The Bills increased their dept at DE significantly with the additions of Mario Williams and Mark Anderson. Adding those two to Chris Kelsay and Alex Carrington gives them some of the best DE depth in the AFC.
Second, Mario Williams is hardly "injury prone" as you claim. He didn't miss a single game his 1st four seasons. The 5 games in 2010 and the 11 games in 2011 were due to catastrophic injury.
Third, the Bills have a healthy Kyle Williams returning. When healthy, Williams is one of the top 5 DTs in the NFL.
As for your evaluation of Mark Anderson, it leaves a lot to be desired.. You overlook that Anderson stepped up his game and was actually decent against the run when put in as a full time player. You also over-look that not all of his sacks came when he was a part-time player. So, the idea that he was only successful in sub-packages doesn't hold water.
Where the Bills are hurting is in their back 7. They have a really good safety in Jarius Byrd, but beyond that, they are questionable. They have the highly talented, but injury prone Terrence McGee. They have the mediocre talent in Leodis McKelvin. They added Stephon Gilmore who zoomed up the charts going from 3rd/4th round pick to mid first rounder. They also have the versatile, but mediocre, George Wilson. Beyond that, they are a whole lot of questions. And that is where they will be beaten in this pass happy league. Particularly if their rotation of DEs can't put pressure onto opposing QBs..