[5][6] In 2019, Mendenhall became the first Virginia coach to bring both the Commonwealth Cup and Jefferson-Eppes Trophy to Charlottesville at the same time, and his Cavaliers also won the South's Oldest Rivalry in the same season.

Mendenhall and his wife, Holly, were prepared to tell their sons about the move to UNLV when Whittingham rejected the offer from BYU and accepted the head coaching job at Utah as Urban Meyer's replacement.

BYU reached its third consecutive Las Vegas Bowl, again winning in dramatic fashion after blocking UCLA's last second field goal to preserve a 17–16 victory.

Mendenhall led BYU to a third-place finish in the MWC at 6–2 and yet another bowl berth in Las Vegas where the team lost to Arizona by a score of 31–21.

[8] BYU became one of only nine schools nationally to be ranked in the top 25 of the final BCS standings each of the past three seasons, with only five teams winning more games than the Cougars over that same time span.

Scott Johnson and Matt Bauman gave BYU multiple Academic All-Americans again while future NFL running back Harvey Unga became the school's all-time leading rusher with his third-straight 1,000-yard season.

After losing BYU's winningest quarterback (Max Hall), all-time leading rusher (Harvey Unga) and consensus All-American tight end (Dennis Pitta), Mendenhall started the 2010 season 2–5 after playing six games against eventual bowl-bound teams.

The change ignited the Cougar defense and the rest of the squad as BYU bounced back to finish the year winning five of its last six to place third in the MWC and earn the program's sixth-straight bowl invitation.

He also named former Cougar and NFL player Kelly Poppinga to a permanent position on the defensive staff as outside linebackers coach.

In 2012, BYU had an 8–5 season—including a Poinsettia Bowl victory over former Mountain West Conference rival San Diego State—and Holmoe announced Mendenhall had extended his contract through the 2016 season.

"[9] Prior to the 2013 season, Mendenhall re-hired Robert Anae as the offensive coordinator and also turned over the defense to secondary coach Nick Howell.

After losing defensive star Ezekiel Ansah as the #5 pick in the 2013 NFL draft, the season started slowly for BYU.

A blowout win against #15 Texas that put the football world on notice was sandwiched between disappointing losses at Virginia and against Utah.

After adjustments by Mendenhall, the team won 5 games in a row including impressive victories against Boise State and Georgia Tech.

Also for the second consecutive year, BYU opened the season on the road in the east coast, beating UConn 35–10 on their home field.

The team would recover though and win 7 of its last 8 regular season games to earn a 9–3 record and an eleventh consecutive bowl invitation, all under Mendenhall.

Mendenhall also thanked BYU for the one-of-a-kind opportunity and agreed to coach the team in the 2015 Las Vegas Bowl against #20 Utah.

[3] Mendenhall had previously turned down the head coaching job at UCLA several years prior to accepting the one at Virginia.

[12] The appointment was viewed by many as a surprise, following intense speculation involving Mark Richt, Jeff Brohm, and Sonny Dykes as candidates,[13][14] and drew comparisons with the 2009 hire of Virginia's men's basketball coach Tony Bennett.

In the press conference at BYU following the announcement of his departure, Mendenhall made note of the similarities to the Cougars when he took over as head coach, having suffered three losing seasons under Gary Crowton at that time.

[16] Things did not go well for the Cavaliers in his first season at UVA however, as the team finished 2–10, last place in the ACC,[17] and he did not coach in a bowl game for the first time in his entire career.

[19] Despite the poor projections, the Cavaliers surprised many by starting the season 5–1, including a 42–23 road win against a nationally ranked Boise State team.

Despite coming off an improved record and a bowl appearance in 2017, Virginia once again was picked last in the ACC Coastal by ESPN and many college football news services.

However, the Cavaliers handily defeated official ACC rivals Louisville, 27–3, again won the South's Oldest Rivalry against North Carolina, 31–21, and upended the No.

The team then regrouped and ended things on a dominant high note with a statement win over South Carolina, 28–0, in the 2018 Belk Bowl.

[20][21] The lopsided victory was seen as a show of strength for not only Virginia and Mendenhall, but for ACC football's standing relative to SEC teams in the runup before Clemson's rout of Alabama for the National Championship.

After opening with a win at Pitt, they proceeded to go undefeated at home, culminating in their first victory over Virginia Tech after fifteen consecutive losses in their rivalry.

The victory capped a 9–3 regular season and secured the program's first Coastal Division title and a berth in the 2019 ACC Championship Game and 2019 Orange Bowl.

The COVID-19 pandemic cast a pall over the season, and the ACC teams played mostly only each other with FCS program Abilene Christian being a late addition for UVA.

After two consecutive losses to North Carolina and Wake Forest, UVA won four ACC games in a row, including wins against Louisville and Miami, each on last-second field goal misses by the opponent.