Briggs called getting teammates properly aligned the most taxing aspect of the assignment. And then there is Trestman's practice system. Plays come off every 16 or 17 seconds, so the defense feels like it's almost always in a two-minute drill.
"It's different," Briggs said. "You've been in a system for a long time. You're now told to change and do things a different way. It just takes time."
The defense has more than held its own in early scrimmages against the new-look offense, but was dealt a blow Monday when backup defensive end Turk McBride was ruled out for the season with a torn Achilles tendon.
The Bears are already without defensive end Israel Idonije, who is now with Detroit, and free agent acquisition Sedrick Ellis, who decided to retire at age 28.
Tucker, the former Cleveland and Jacksonville defensive coordinator, expects veterans like Briggs, Tillman and Julius Peppers to lead the way through injuries and whatever other changes are dictated by the new regime
"We want to build on the foundation that's been laid and what's been done," he said.
NOTES: Left tackle Jermon Bushrod missed Monday's practice with a right calf strain that occurred in the warm-up period before practice. Trestman said he's day to day. Jonathan Scott replaced Bushrod at left tackle. ... Wide receiver Brandon Marshall was given Monday's practice off and the entire team will be off on Tuesday. The idea is to give Marshall extra rest as he is coming off hip surgery in the offseason. ... Defensive end Cheta Ozougwu sustained a slight hamstring pull and is day to day.