UNLV football has witnessed new highs following back-to-back Mountain West Conference title game appearances. The Rebels opening eventually attracted Dan Mullen to take the head coaching job this offseason. But Mullen now is dealing with his first sudden staff change.

Mullen is turning to an interim DC ahead of his Rebels debut. Ralph D Russo of The Athletic revealed the development out of Sin City Monday.

“UNLV announces defensive coordinator Zach Arnett, who did a one-year stint as Mississippi State HC, has resigned for personal reasons,” Russo shared via X.

The Rebs already have his replacement in place. And he's a past NFL assistant with ties to Vegas.

“Associate head coach Paul Guenther was named interim defensive coordinator,” Russo said.

This is the first major change for the new Rebels head coach. Mullen did lose two starters from the L.A. Bowl team two days after the game.

Will Dan Mullen search for longer term DC at UNLV? Notable candidates

UNLV Rebels defensive back Tony Grimes (0) tackles Boise State Broncos wide receiver Latrell Caples (3) during the second half at Albertsons Stadium. Boise State beats UNLV 21-7. Mandatory Credit: Brian Losness-Imagn Images
Brian Losness-Imagn Images
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Guenther has been a DC before in Sin City. He served as the Raiders defensive coordinator during the 2020 season.

Guenther reunited with his old Ursinus College friend and roommate Mullen in joining the UNLV staff. But will Guenther be the defensive coordinator moving forward for the Rebs?

Arnett's decision comes during spring football practices at UNLV. The timing of the decision becomes odd for the Rebels. Guenther steps in on an interim basis — but likely will have a chance to retain DC duties depending on how UNLV plays. Still, there are notable candidates who could emerge if Mullen and UNLV reopens the position after the season.

Former Fresno State interim head coach Tim Skipper is a past UNLV assistant. Skipper developed a stout recruiting reputation in Sin City with the Rebels. He also helped build the recruiting classes under Jeff Tedford from 2022 to 2023 — resulting in the MWC title during the former season. Skipper was last rumored to be heading to Florida back on Jan. 31 — where he's a former assistant under Jim McElwain.

Bert Watts is another with both previous Fresno State and MWC ties. He also shares an SEC connection with Mullen — having previously coached at Auburn. Watts also was with the Denver Broncos as linebackers coach.

Or Mullen can wait until after the season to see which programs clean house on the defensive side. Then make a run at who's available.