If Cincinnati Bengals defensive coordinator Mike Zimmer leaves for one of two open head coaching positions in Miami or Tampa Bay, the Cincinnati Bengals will instantly be in a search for a replacement. Though this writer, yours truly, believes that the replacement would eventually be defensive backs coach Kevin Coyle, another favorite remains in former Jacksonville Jaguars coach Jack Del Rio.
However Del Rio has also been mentioned as favorite for the defensive coordinator position in Atlanta, likely due to his association with head coach Mike Smith on Baltimore's coaching staff (similar to the conjecture putting Del Rio as a favorite in Cincinnati).
According to Jay Glazer of Fox Sports, the Atlanta Falcons have hired Mike Nolan as their defensive coordinator on Tuesday.
None of this really matters until Mike Zimmer's future is eventually known. There is still a chance that the Bengals retain Zimmer the longer the process goes on.