LAS VEGAS — Paul Guenther was never supposed to spend his first spring at UNLV installing his own defense. He arrived as associate head coach and safeties coach, with Zach Arnett hired to coordinate the defense, then took over after Arnett resigned with the Rebels already five practices into spring football.

That left Guenther trying to establish his system while learning what a largely rebuilt roster could handle. The players were learning him at the same time, without getting a complete spring under the coordinator who would eventually run the defense. Dan Mullen has repeatedly pointed to that situation when discussing why the expectations should be different in 2026.

“He was put in a tough situation last year,” Mullen said. “Not only did we not really know what the players did well, they did not even get a spring to learn the defense.”

The roster situation is different now, too. UNLV enters 2026 with 29 returning lettermen, including 16 on defense, after entering Mullen’s first season with only 17 total lettermen and two returning starters. Only three defensive starters officially return, but Guenther has considerably more players who have practiced in the defense, sat through the meetings and experienced what happens when a call or adjustment breaks down.

UNLV also filled holes with experienced transfers at every level, giving Guenther more established options around the players who stayed. That combination of retention, outside additions and an entire offseason in the same system is the basis for the higher expectations.

Why Year 1 Was So Uneven

The final numbers tell both sides of Guenther’s first season. UNLV allowed 28 points and 419.1 yards per game, including 177.4 rushing yards while opponents averaged 5.2 yards per carry. The Rebels still produced 30 sacks, 66 tackles for loss and 14 interceptions.

That was Guenther’s first season in one line. UNLV could create havoc. It could not consistently control a possession.

The middle of the season exposed the problem. Air Force produced 603 yards, Boise State followed with 558 and New Mexico scored 40 points two weeks later. The offenses attacked UNLV differently, forcing Guenther to adjust from the NFL’s relative week-to-week consistency while determining how much of his own system the Rebels could execute.

Some of the biggest problems started before the ball was snapped. Lucas Conti said players could recognize an adjustment without getting the information communicated across the defense quickly enough, creating missed gaps and broken coverages even when somebody had identified what the offense was trying to do.

“This is our second year,” Conti said. “Last year was our first year seeing it. It’s like seeing a real NFL defense. I think we’re going to be a lot more capable of running it to its expectation.”

That communication improved as the season went on, and the results changed with it. UNLV surrendered 144 points during a three-game stretch against Air Force, Boise State and New Mexico, then gave up 63 over its final four regular-season games. The pass rush also went from one sack over a four-game stretch to 20 over the final five regular-season games.

The defense was not suddenly fixed. Boise State scored 38 in the Mountain West championship, and Ohio rushed for more than 200 yards in the Frisco Bowl. What changed was that UNLV began putting together longer stretches of competent defense instead of depending on one sack or turnover to save the possession.

Guenther now gets to build from that point rather than spending August establishing the foundation.

“This time last year we were still learning our base coverages,” Guenther said. “Now it’s like we’re on to a bunch of other stuff.”

Retention and New Additions Give the Front Seven More Options

Guenther continues to build his defense from the line of scrimmage, which makes the returning pieces up front important to any Year 2 improvement.

“You got to be good up front,” Guenther said. “If you look at my career, I’ve built so many things off of D-line.”

Lucas Conti and Cohen Fuller give UNLV two experienced interior players. Conti finished last season with 22 tackles, four tackles for loss and 2.5 sacks, while Fuller had 27 tackles, 3.5 tackles for loss and two sacks. Mullen views both as returning starters and expects their second season in the defense to result in more than simply knowing where to line up.

“They gotta be a force and a presence inside for us to try to dominate the middle of the field on the defensive side of the ball,” Mullen said.

Landen Thomas also returns after 13 tackles and 2.5 tackles for loss, while Elias Rudolph has another season in the system on the edge. Mohamed Altayeb and Tennessee transfer Herb Gray give UNLV additional interior options behind a group Guenther believes is deeper than it was last season.

“We have really two sets of lines in there, and there’s not a big drop-off when we put the other guys in there,” Guenther said.

The deeper front still has to produce, and UNLV also has pressure production to replace across the defense. Tunmise Adeleye led the Rebels with six sacks last season, while Jaheem Joseph and Aamaris Brown each had 3.5. Those three accounted for 13 of UNLV’s 30 sacks, meaning the additional depth has to become actual pressure rather than simply more players available to rotate.

The linebacker room gives UNLV another mix of retention and additions. Blesyng Alualu-Tuiolemotu returns after starting 12 games and making 61 tackles with five tackles for loss, while Kamuela Ka’aihue played all 14 games and finished with 23 tackles and two tackles for loss. Both have already spent a season inside Guenther’s defense.

Cam Santee gives UNLV the most significant new production in the room after making 110 tackles, 14 tackles for loss, 4.5 sacks and forcing five fumbles at Holy Cross. Dee Crayton adds 30 games of Clemson experience, giving the Rebels another player who has already played meaningful college football rather than forcing the depth chart to rely entirely on projection.

Justin Flowe gives UNLV additional experience, but his current role is different from the primary inside rotation. He contributed primarily on special teams last season and has worked at the Jack/edge position and with the third group during camp, making him experienced depth rather than one of the four primary interior options.

The linebacker coaching structure is different as well. Mike Scherer is back after coordinating Purdue’s defense last season, allowing him to handle the inside linebackers while Bam Amina works more specifically with the outside group. Scherer already knows several returning players from his previous UNLV stint, although this is his first season working within Guenther’s defense.

Mullen believes that college experience complements what Guenther brings.

“Mike comes in as a really good young football coach that has more experience in college playing all these teams in this league,” Mullen said. “Paul is this veteran coach.”

The front seven therefore has more established options, but its improvement cannot be judged by depth alone. UNLV still has to replace pressure production and improve a run defense that allowed 5.2 yards per carry.

The Secondary Retained a Base and Added Experience Around It

The secondary follows the same pattern. UNLV lost significant production, but Guenther retained enough players that he is adding newcomers around an existing group rather than rebuilding the entire back end.

Jake Pope gives the Rebels the most established returning player in the secondary after finishing last season with 81 tackles, three tackles for loss, 1.5 sacks, one interception and five pass breakups. Tre Fulton added 33 tackles, four pass breakups and a forced fumble, while Quandarius Keyes finished with two interceptions and six pass breakups. Mumu Bin-Wahad recorded 32 tackles, four quarterback hurries, a forced fumble and a fumble recovery.

Denver Harris also returns after a limited first UNLV season, while Logan Christensen gives Guenther another second-year safety who spent last season in the system. Those snaps matter because the secondary was part of the same communication problem as the front seven. Returning players have already experienced what happens when a front adjustment changes a coverage responsibility and the message does not reach everybody quickly enough.

The harder part is replacing the plays that left.

UNLV lost 11 of its 14 interceptions from last season. Laterrance Welch had five, Aamaris Brown had four and Marsel McDuffie had two. The returning secondary has more experience in Guenther’s defense, but it cannot simply assume that familiarity will reproduce the same takeaway numbers.

Avery Helm gives UNLV its most experienced addition at corner after playing 37 games with 24 starts between Florida and TCU. Landyn Cleveland adds another veteran option after playing at Oklahoma State, while Tony-Louis Nkuba gives the Rebels a younger developmental piece behind them.

That is the balance Guenther has throughout the defense. The Rebels did not retain everyone they wanted, and the newcomers are not walking into positions with nothing established around them. Pope, Fulton, Keyes and the other returners provide a base, while Helm and Cleveland add experience where UNLV lost production.

The next step is turning that continuity into fewer explosive mistakes while finding new sources of turnovers.

What Year 2 Improvement Actually Has to Look Like

The higher expectations are not based on UNLV simply having more players. The added depth only matters if it changes how the defense plays.

UNLV does not need more sacks or interceptions to prove Guenther’s defense can create havoc. Thirty sacks and 14 interceptions already established that.

The improvement has to come everywhere between those plays.

The defensive line has to make early downs harder and replace the pressure production that left. The linebackers have to fit the run better and communicate without one missed adjustment opening the middle of the field. The secondary has to replace enough of the lost takeaway production while cutting down the explosive plays created by busted assignments.

Those are the areas that have to move the overall numbers. UNLV cannot again allow 419.1 yards per game and 177.4 rushing yards at 5.2 yards per carry and call the defense significantly improved.

The third-down defense gives Guenther something worth carrying forward. During the regular season, opponents converted only 29.4% of their third downs. The next step is not necessarily becoming dramatically better on third down. It is creating more difficult third downs in the first place.

A defense cannot live in third-and-8 if it gives up six yards on first down.

That is where the front, linebackers and secondary have to become one defense. Conti and Fuller controlling the middle helps keep blockers away from Santee and Alualu-Tuiolemotu. Better linebacker fits make it easier for Pope, Keyes and the rest of the secondary to remain disciplined instead of compensating for something breaking down in front of them. Cleaner communication gives Guenther more freedom to disguise what is coming without asking players to process more than they can execute.

More familiarity does not automatically turn a defense that allowed more than 400 yards per game into a good one. UNLV still has pressure production and takeaways to replace, and only three official defensive starters return.

There are also fewer explanations available if the defense looks as disjointed as it did early last season. Guenther has had a spring as coordinator, the staff has defined responsibilities and 16 defensive lettermen return around the transfers brought in to address specific needs.

That is why the expectations should be higher without assuming the improvement has already happened. The reasons are there in the retention, the additions, the late-season progress and the full offseason. Now the defense has to turn them into something that survives once an opponent starts changing the picture.

Guenther believes the difference already appears on tape.

“If you looked at our tape from a year ago to tape now, there’s a huge improvement,” Guenther said. “But we’ll see what happens when the ball is flying.”

Last season, UNLV spent months trying to get Guenther’s defense to look like one defense. By the end of the year, it finally started getting there.

The expectation in Year 2 is that it starts there and keeps growing.