If it ain't broke then why fix it? The Pittsburgh Steelers have possessed the most consistently dominant pass rush in the NFL over the past four seasons. They spent money in free agency to strengthen their secondary during this time, and utilized an aggressive mentality to turn draft capital into solutions at a couple of key defensive positions in the middle of the field.
The Steelers defense steadily improved each season as guys like Bud Dupree and Stephon Tuitt finally enjoyed breakout seasons with the benefit of experience and good health allowing them to stay on the field and productive.