Provo • Back in April, BYU safety Micah Harper was asked to describe quarterback Jake Retzlaff’s playing style.

“Jake, he brings a different throwing motion that we are not used to,” Harper said at the time. “Sidearm, a little Patrick Mahomes. He also can make plays with his legs.”

The comparison to the Kansas City Chiefs quarterback raised eyebrows. It would be a stretch to put the former junior college star on the same level as the Super Bowl champ. But it underscored a point: Retzlaff is a mobile quarterback who is unafraid to make throws from odd angles. His style stands in stark contrast to incumbent starter Kedon Slovis.

Nearly seven months later, Retzlaff will get his first start at BYU. Slovis has been dealing with injuries for the last several weeks, The Salt Lake Tribune reported on Thursday, and will rest against West Virginia.

That means Retzlaff and his quirky style will now run BYU’s offense against the Mountaineers.

The natural question is, how ready is Retzlaff to start and what changes can BYU expect from its new quarterback?

On the surface, Retzlaff is known for his arm talent. He threw for 4,596 yards, 44 touchdowns and 14 interceptions in 13 games last year at Riverside City College in California.

But the number one change from Slovis might be Retzlaff’s mobility. Slovis was mostly a pocket quarterback and Retzlaff can get out and run.

Over the last few weeks, as the offense struggled to gain over 300 yards, many wondered whether BYU could use a more mobile quarterback. In the past, BYU had Zach Wilson and Jaren Hall (who both ran for more than 625 yards in their career).

This year, BYU has asked Slovis to execute many run-pass-option plays like a mobile quarterback. It’s led to varying results. That shouldn’t be an issue with Retzlaff, who ran for over 500 yards last year.

Offensive coordinator Aaron Roderick would “probably call the game slightly different if I’m in versus if Kedon’s in,” Retzlaff said last month in an interview with The Salt Lake Tribune. “I think I have a more RPO-type game style. I’ll tuck and run the ball a little more than he does. It’s just little differences like that. I feel like there’s definitely a lot in this offense that I can do really well with.”

From a passing perspective, Retzlaff believes he had a strong command over the playbook. For him, the most challenging part of this offense was getting used to BYU’s expanded personnel packages.

At Riverside, Retlzaff mostly worked with 10- and 11-personnel (meaning one running back and no tights, or one running back and one tight end). At BYU, Roderick can run 11, 12 and 13-personnel. BYU will often pass out of 12 personnel too (meaning one running back and two tight ends).

“The previous offenses I ran, they weren’t as personnel expanded,” Retzlaff said. “Here we can run and pass out of 11 and 12 — any way we want to get to it. I think our tight ends are super versatile, which is new to me a little bit. I mean, I had a good tight end last year. But like these guys, having a lot of tight ends on the field doing a lot of different things is pretty interesting.”

BYU also uses motion and shifts that weren’t a big part of Retzlaff’s past offenses. Perhaps the most unique difference is Roderick will ask his quarterbacks to go under center at times. Retzlaff never did that in high school and only used it for quarterback sneaks in college.

Sometimes quarterbacks don’t like being under center. For a brief second, they have to turn their back to the defense. In shotgun, quarterbacks can see the field the whole play. Retzlaff is acclimating to that.

“It was a matter of getting used to that,” Retzlaff said. “Shotgun, you’re always facing the field. Even if you are faking a handoff. You can identify what individual players are doing. When you turn around [under center], you are just gonna take a picture [of the defense in your mind] and then come back and fill in the picture right away.”

Retzlaff did say he liked the versatility being under center can bring to an offense.

“Both have their strengths,” he said. “Like understanding you can get a lot better play fakes under center. Gonna get better bootlegs, naked boots, you know, different deeper concepts. Because those linebackers might be on the run and the safeties might be packed inside.”

Slovis was more comfortable under center right away. He ran those concepts at Pitt. Retzlaff often picked Slovis’ brain during Monday film sessions to see what Slovis was looking for.

Retzlaff said last month he was more comfortable under center. Throughout this season, he received about one-third of the practice reps, he said.

Overall, he believed he had a strong command over the playbook and the responsibilities. In high school, he was asked to do almost everything pre-snap. That included calling out protections from the offensive line.

The level of responsibility for a quarterback in BYU’s offense varies.

“It’s not too much at all, so we don’t have to make seven decisions for every play,” he said. “But there’s definitely some checks that we got to get to.”

In his first start, Retzlaff will be on the road in Morgantown. BYU likely needs a win in the next two weeks to make a bowl game. And it appears Retzlaff will feel as prepared as he can be.

“A-Rod, just as well as anybody if not better, knows how to call it to his quarterback,” Retzlaff said.