It's been a busy day at Halas Hall, and new head coach Marc Trestman is already making significant changes to the Chicago Bears coaching staff. Specifically, nearly a complete overhaul.

The team's official Twitter account reports:

Assistant coaches Tice, Babich, Bates, DeBord, Drake, Holt and Spencer informed they won't be retained.

For those unfamiliar, that OC Mike Tice, LB Coach Bob Babich, QB Coach Jeremy Bates, TE Coach Mike Debord, WR Coach Darryl Drake, OL Coach Tim Holt, and RB Coach Tim Spencer.

Earlier today, we learned that DC Rod Marinelli would not be re-joining the team in 2013, but that was a decision he made himself, not Trestman.

Many Chicago Bears fans have been calling for a complete overhaul of the front office and coaching staff, so perhaps this is what you had in mind. New HC Marc Trestman will bring his brand of offense to Chicago, and has completely turned over the offensive coaching staff.

The last remaining Lovie Smith holdover was former DC and current LB coach Babich. He is among the recent casualties.

Stay tuned...