Oakland showed improvement up front during his year in charge. It went from last in the NFL with 13 sacks in 2018, 17 fewer than any other team, to 24th in that category (32 sacks). It also improved from 30th in run defense (140.6 yards per game) to eighth (98.1 YPG).
Buckner spent 12 years in the NFL as a defensive tackle before retiring after the 2005 season.
"My philosophy with defensive line is pure fundamentals," he told reporters last January. "Technique, assignment and constant violence every snap. Bring a relentless effort to want to get there. As hard as you can for as long as you can, then the next guy give me the same effort. Because iron sharpens iron."
His success with the Raiders should earn him another opportunity elsewhere almost immediately.
Brentson Buckner @faithbeforefame
God doesn't make mistakes. When He decides my time is up, I don't question it. I was blessed to coach a great group of Raiders. I had the pleasure of experiencing RAIDER NATION! I'm appreciative for Gruden blessing me with that opportunity! #FAITHBEFOREFAME 1love! No hate
Meanwhile, Marinelli wasn't retained by the Dallas Cowboys after seven seasons as the team's defensive coordinator and defensive line coach.
The Cowboys failed to reach expectations in 2019, which led to widespread changes to the coaching staff, led by former Green Bay Packers coach Mike McCarthy taking over Jason Garrett as head coach.
In December, Marinelli told Clarence E. Hill Jr. of the Fort Worth Star-Telegram he shouldered the blame for the team's struggles defensively after three straight losses.
"I will take full responsibility," Marinelli said. "Things we are coaching. Obviously I am not emphasizing well enough and we didn't do it. That's a reflection on me. It's cut and dried."
His experience in the role is virtually unmatched, though. He served as defensive line coach with the Utah State Aggies for six years starting in 1976, and more than four decades later he's going back to those roots while working under Raiders defensive coordinator Paul Guenther.