There is a reason that the team isn't trying to replace Bullocks......he actually executed his assigments very well. The problem was the assignment. Notice that the safeties took over a lot of the LBers coverage assigments in order to free up the front seven to play the run. Opponents then manipulated those assigments to free up deep routes.
It's no accident that the Saints dramatically improved the run d without changing personnel. It came at thhe cost of deep coverage.