NORMAN, Okla. —  As Bob Stoops prepares to lead Oklahoma onto the practice field this spring, the new faces in prominent roles are plentiful.

Landry Jones will be noticeably absent after spending the past four seasons as the starting quarterback, first as Heisman Trophy winner Sam Bradford’s replacement and then finding his own place in the Sooners’ record books. Receiver Kenny Stills and safety Tony Jefferson left early to enter the NFL draft.

Perhaps strangest of all, though, is the influx of new assistant coaches. Jerry Montgomery, Bill Bedenbaugh and Jay Boulware join Stoops’ staff this spring, the first time Oklahoma has replaced three assistants in the same offseason under Stoops.

Over the past two offseasons, five assistants — more than half of the staff — have been replaced in a massive overhaul.

“There’s always different reasons for that when those things happen,” Stoops said Thursday. “We’ve had coaching changes over 15 years at different times, in different ways. We’ll adjust to this one the best we can.”

Stoops refused to provide any specifics on why defensive tackles coach Jackie Shipp and offensive line coaches James Patton and Bruce Kittle were let go, saying those were “private conversations.” The changes have come as Oklahoma has been out of the national title chase for the past five seasons.

All three of the newcomers were from established programs — Montgomery from Michigan, Bedenbaugh from West Virginia and Boulware had yet to really start at Wisconsin after a stint at Auburn — and they reflect a youth movement on the staff.

“We put them all right to work when they got here,” offensive coordinator Josh Heupel said. “It’s been a lot of fun, getting some new energy, new ideas, guys that see things from a different perspective, seeing your program from a different perspective, too, looking from the outside in. We’re excited about the things that they bring to the table.”

Now that the staff is complete, the roles have been defined.

Stoops said that Bobby Jack Wright, who had been in charge of defensive ends, will now oversee the cornerbacks. Defensive coordinator Mike Stoops will also be the safeties coach as the Sooners put more manpower in the secondary in the pass-heavy Big 12.

Montgomery will coach the entire defensive line, which previously had two coaches — one for tackles and one for ends. Tim Kish remains in charge of the linebackers.

With speculation that the Sooners would be switching from a four-man defensive front to a three-man front, both Stoops brothers indicated the reality is they plan to use both. To some degree, they’re still searching for the best approach to use against the Big 12’s increasingly productive offenses.

“We’ve got a lot of work to do in trying to re-establish ourselves as one of the top defenses. At times, I thought, last year we played well. But down the stretch, when we really got against some really good offenses, we didn’t play nearly as good as we need to here at Oklahoma,” Mike Stoops said. “We’re always going to have great expectations for what we expect to do when we step on the field.”

Soon, the focus will move from the new coaches to the competition to replace Jones. The Sooners begin spring practice this weekend, with sessions planned Saturday and Sunday. It’s unlikely there will be a new starter named this spring, which ends with the Red-White game on April 13.

“We generally haven’t made the decision real early. There comes a certain time where somebody’s got to start and be ready for it. I think most of our battles have continued through the summer, through two-a-days, for good reason in our mind,” Bob Stoops said. “We want to see the continued competition.

“We may, in our mind, already know who has the edge in our eyes but let’s see if he’s had a good summer, let’s see if someone didn’t come back and maybe improve more than he did in the summer and overtake him. So, we want to see that competition work through a good part of the summer and two-a-days. I would anticipate that being the same thing.”

Junior Blake Bell is the only one of the three candidates with game experience. He’ll be competing against sophomore Kendal Thompson and redshirt freshman Trevor Knight. Bob Stoops said longtime backup Drew Allen will not remain with the team this spring and plans to transfer after he graduates.

“I think with all three of these guys, we have guys that are very competitive, very confident, athletic, can make plays, can do anything that we’re asking them physically as far as running the football but then certainly can push ball down field as well,” Heupel said. “So, I think all these guys will compete in a great way.”

Heupel said it remains to be seen whether Bell’s experience in the short-yardage “Belldozer” package and mop-up duty will give him an advantage.

“We’re going to name a guy when he’s earned it. That’s what we’ve always done here,” Heupel said. “That position, it’s extremely important, I think, for that guy to go out and earn that position, earn the confidence of guys around him, earn the trust of the people around him, so he can ultimately lead that group, that offense the way that we want him to.”