Watch Now: How Las Vegas is prepared for wagering with the Raiders moving to town (1:03)

There's an unexpected change within the Oakland Raiders coaching staff. Granted, it's not nearly as sweeping as what took place in early January due east, where the Dallas Cowboys parted ways with Jason Garrett -- along with most of his coaching staff -- and hired Mike McCarthy, but what happened was Jon Gruden apparently had his eye on one Cowboys coach in particular throughout it all. To that end, when defensive coordinator Rod Marinelli was informed he wouldn't be retained by the Cowboys, Gruden put a plan into action. 

The Raiders head coach fired defensive line coach Brenston Buckner, and has now officially replaced him with Marinelli -- the team announced -- for the 2020 season. Buckner joined the Raiders in 2019 and the team saw their sack tally more than double from only 13 the year prior to 32 in 2019, having also improved greatly in run defense. His coaching prowess made the move surprising, because Buckner did exactly what he was brought on to do, while Marinelli was coordinating a Cowboys defense in 2019 that took massive steps in the wrong direction. 

Still, Gruden wanted a reunion, and he got his wish.

The 70-year-old was rumored to be mulling retirement in the previous two off-seasons before doubling down on his commitment to remain with the Cowboys. He's had success at times in Dallas, but it was too inconsistent for McCarthy's tastes, with Marinelli understanding he'd be a casualty of the regime change -- replaced by Mike Nolan in Dallas. 

"Only thing I know is they can't send me back to Vietnam," Marinelli said jokingly, via Jane Slater of NFL Network. "After that it's cake. Outlook is always forward."

No Vietnam. Instead, Vegas.

Unfortunately for Buckner, as well as he performed in his one-year stint in Oakland, Marinelli and Gruden have a history that more than likely fuels this reunion. Marinelli served as assistant head coach and defensive line coach under Gruden for several seasons in the early 2000s with the Tampa Bay Buccaneers, before the former left to take the head coaching position with the Detroit Lions. The two helped engineer the first Super Bowl victory in Buccaneers history, and Gruden is hoping to rekindle that magic as the Raiders ready for their move to Las Vegas in 2020.

Buckner, who's served as defensive line coach for three teams in the last seven seasons, quickly landed on his feet by becoming the new defensive line coach for the Arizona Cardinals.