The story that Nix gave prior to the season was that the Bills were "all set" at OLB (edge rushers). Apparently, Merriman was the entirety of the plan for the season. Despite Merriman obviously being injury prone. Couple that with the inability of the guys drafted last year to do squat, they end up with a DE and DT starting at OLB. Now some will say it is just a matter of bad luck that Merriman got injured, but it simply is not a matter of luck to have no backup plan; heck, they haven't even tried to get any better by bringing in street free agents, unless maybe this guy that can jump out of a pool is it.
The Bills coaches are on a different page and continue to run this hybrid defensive scheme, which seems like an indication that they don't believe after two off-seasons that they have been given the requisite talent in the front-7 to run a base 3-4. Either that or they think they have an abundance of versatile talent and they can run any defensive system from down to down. Either way, the proof is in the pudding and the defense can be scored on almost at will. The Bills have spent their draft day resources both years on fixing the defensive front-7, and they continue to have big problems.