I don't think Dom has forgot how to coach, not at all, but I do think it is time for a change.
With the amount of talent that we have at all three levels of this defense, yes even the Backers, we should be much more consistent than we are today.
As to whom I would target, I think I would start with Dave Aranda currently at LSU. I think he could be convinced to give the Pro game a run while building a resume to become a head coach eventually.
He was able to take a 4-3 roster and build a 3-4 defense that has enough wrinkles in it to manufacture pressure and gets his players to hit their potential. While Wisconsin has remained strong on that side of the ball, we are still seeing his finger prints on that defense... and the players he helped develop.
My opinion, the guy can flat out coach.
"The oranges are dry; the apples are mealy; and the papayas... I don't know what's going on with the papayas!"