The dominos have begun to fall with the news that Jim Tomsula has been promoted from defensive line coach to head coach of the San Francisco 49ers.

According to an NFL source, the coaching staff left over from Jim Harbaugh’s tenure will be undergoing a total housecleaning. Offensive line coach Mike Solari and running backs coach Tom Rathman are both headed out the door, with Rathman expected to join Greg Roman in Buffalo. The source said Vic Fangio is on his way out as well, but that both Solari and Rathman would have stayed if Fangio had been promoted to head coach.

As for the incoming staff, the source says that Marc Trestman and Jason Tarver are the 49ers’ main targets for offensive coordinator and defensive coordinator. Trestman was fired after going 5-11 in his second full season as the Chicago Bears’ head coach and was the 49ers’ offensive coordinator and quarterbacks coach in 1995 and 1996. Tarver was the defensive coordinator for the Raiders from 2012 until 2014.