The San Francisco 49ers have been total overhaul mode since hiring head coach Chip Kelly, and they have now fired their defensive coordinator Eric Mangini, according to ESPN's Adam Schefter. The 49ers also reportedly made a big move for their offense on Friday, as they hired Detroit Lions assistant Curtis Modkins to become their next offensive coordinator.

The 49ers reportedly offered Houston Texans linebackers coach Mike Vrabel the defensive coordinator position, but he has since turned it down and reportedly has signed a new contract in Houston. The 49ers are clearing house after one season with former head coach Jim Tomsula and are now trying to piece Kelly's coaching staff together.

On the defensive side of the ball, the 49ers have hired former Tampa Bay Buccaneers linebackers coach Hardy Nickerson to coach the same position in San Francisco, according to Alex Marvez of Fox Sports. Nickerson had a 16-year NFL career and finished his career with five Pro Bowl appearances. New reports surfaced Saturday morning that Nickerson will coach the 49ers' inside linebackers, and 49ers linebackers coach Jason Tarver will coach outside linebackers and could become their next defensive coordinator, according to Bleacher Reports' Jason Cole. Tarver has reportedly been told that he is their top internal coaching candidate to take over as their defensive coordinator, but the team will still interview outside coaches.

Kelly is clearly trying to get his coaching staff in order, as the San Francisco 49ers still has a ton of work that needs to be done before the 2016 season.