Las Vegas • Freshman Joe Critchlow became BYU’s third starting quarterback of the 2017 season on Friday night as the Cougars faced UNLV at Sam Boyd Stadium.

Critchlow was filling in for Tanner Mangum, the eight-game starter who sustained a season-ending Achilles injury in last week’s 20-13 loss at Fresno State. Sophomore Beau Hoge, who had started in two games and relieved Mangum last week, was injured and not able to play, coach Kalani Sitake told KSL Radio on his pregame show.

“Beau is not going to be able to go, so we will have Joe Critchlow take the first snap, and Kody Wilstead will be behind him,” Sitake said. “Just waiting to see if we need him. Hopefully, Joe can get it going — they’ve had a pretty good week of practice.”

The Cougars have used five quarterbacks this season, counting snaps that QB-turned-RB Austin Kafentzis has taken in the wildcat formation. Sophomore Koy Detmer Jr. played against Utah State and was listed by Sitake as the third-stringer before Friday’s game.

Critchlow became the fourth freshman to get a start at QB for BYU since 2010, joining Jake Heaps (2010), Taysom Hill (2012) and Mangum (2015). Drew Miller (1997) is the only other true freshman to start at QB for BYU.

Critchlow completed 10 of 14 passes for 119 yards and a touchdown to Aleva Hifo in the first half.

Shoaf eyes offseason weight gain

BYU left tackle Thomas Shoaf was listed in the pre-game two-deep guide as weighing in at 275 pounds. That might be generous. The sophomore from Indiana is closer to 250 pounds.

“Not the focus right now,” he said Tuesday when asked about his efforts to gain weight. “Just focused on helping the team out, staying strong, staying healthy, and doing what I can. Once the season is over, I will focus on gaining weight for next year.”

Healthies unit, by far

The same five offensive linemen — Shoaf, left guard Keyan Norman, center Tejan Koroma, right guard Tuni Kanuch and right tackle Austin Hoyt — have started all 11 of BYU’s games this season. While every other position group has been hit hard by injuries, the big linemen have played injury free.

“Every team this late has got their bumps and bruises, but we have been very blessed and very lucky to avoid major injury, knock on wood,” Shoaf said. “Our starting five is [solid] and that comes from having a solid senior core. They have a lot of strength and they have put a lot of years into preparing themselves and taking care of their bodies.”

Briefly

Tight end Moroni Laulu-Pututau, who has not played this season, confirmed he sustained a Lisfranc foot injury two days before the opener against Portland State and plans to return next season when he is 100 percent healthy. … The alumni flags were carried out by receiver Mike Johnston (1991-95), receiver Jim Edwards (1981-86) and linebacker Larry Miller (1975-76).