Our defense has been playing schemes called by our defensive coordinator, Ted Roof, and he has been making those calls based on the personnel he currently has on his roster; personnel that was signed, for the most part, to play in a 3-4 defense rather than a 4-3-4 defense or a 4-2-5 defense.
To overcome what are current "physical limitations" on our current roster, Roof originally employed a bend but dont break style of defense, which, has times, given us occasional stops that has given the team a chance to win close games. However, it has also caused us to get burned on more than one occassion, so Roof appears to be "experimenting" with becoming a more aggressive/attacking style of defense, which makes more sense as players on the current roster have either now been playing under his system for a couple of years, or were recruited specifically by him and are more "physically suited" for his style of defense.
If things continue under this path, I believe our defense will continue to be more aggressive and be more effective the rest of the season.