Roughly 15 percent of young adults ages 25 to 35 were still living at home with their parents in 2017, according to a Pew Research Center study.

Lincoln Riley took over an expansive college football factory at an age when some are still sorting out adulthood. And the question of whether he can do this — lead Oklahoma to glory as head coach — has been altered to, can he do it again?

Riley, 34, faces a challenge equally difficult as last season when he succeeded Bob Stoops. The Sooners’ run to the 2017 College Football Playoff, and nearly the national title game, has buoyed expectations.

“He’s a young Tom Landry,” former Dallas Cowboys vice president of player personnel Gil Brandt told The Transcript.

Under Landry’s signature fedora swirled a universe of intelligence. He coached the Cowboys to 250 victories, including two in the Super Bowl. He is credited for inventing the popular 4-3 defense.

That’s some comparison.

It exists because Riley’s wits have their own reputation now. He has broadened OU’s footprint on the recruiting trail — the Sooners’ 2019 class is on pace to be one of the school’s best in years — while still calling plays and coordinating the team’s offense, which produced a nation-best 8,114 total yards in 2017. Reportedly 28 NFL teams asked Riley about his offensive philosophies during the offseason.

His life is still on fast-forward.

“Some guys just mature a little faster than others,” OU co-offensive coordinator Cale Gundy said. “Some guys move in a direction a little bit faster than others.”

Riley’s first try at this wasn’t perfect.

He learned to time-block his duties as head coach and coordinator and began appreciating the value of delegation. OU steadily underwent its biggest staff overhaul in years. The most vital support positions — director of operations and strength coach — both turned over, as Matt McMillen and Jerry Schmidt moved on with their lives after a combined 38 seasons in Norman.

Six significant hires have been made under Riley’s watch: Ruffin McNeill, Shane Beamer, Bennie Wylie, Courtney Viney, Clarke Stroud and Bob Diaco. Among the group is two former head coaches (McNeill and Diaco), a former Broyles Award finalist (Beamer), a former dean of students (Stroud), a 20-something recruiting specialist (Viney) and a former fitness contestant from reality television (Wylie), whose knack for social media fits within Riley’s strategy to promote the program to young faces.

“I think he’s allowing people maybe around him to handle being in charge and handling things, where it’s not him feeling he has to be in charge of everything,” Gundy said. “I think that’s a more comforting feeling for him, with people — not only coaches — but off the field people in our office helping out.”

Those minds can help Riley keep the pace he has set for himself, but they don’t hold every answer. Heisman Trophy quarterback Baker Mayfield was a generational type player, instrumental to OU’s success last season. Riley has coached no other full-time starting quarterback since he began coordinating OU’s offense in 2015.

“It’s college football. It’s not the NFL,” Riley said. “You aren’t going to have guys for 10 years. You are going to have guys for three, four or five years. You are always going to have some major turnover somewhere. So you get used to that and you enjoy the different challenges of piecing together a team with new parts. This year feels no different in that way.”

It’s different in other ways.

Riley has embraced things he can control, such as rearranging OU’s preseason schedule, moving up media events by nearly two weeks so the quarterback competition he would oversee wasn’t disrupted.

Also, from addressing troubling issues at Ohio State, to his opinion that players ought to be able to sell the personal athletic gear given to them by their schools — a direct disagreement with the NCAA — Riley’s a little more forthcoming with his thoughts on the world around him.

His clock ticks fast and he largely keeps up.

One year ago during his first fall camp practice as head coach, he momentarily forgot he was the one responsible for breaking down the team huddle.

And now?

“I feel a little more settled,” Riley said. “It's not moving quite as fast for me.”