ASHBURN, Va. -- The challenge for opposing offenses next season and beyond will be combating the Washington Football Team's defensive line. The challenge for Washington will be trying to keep them together as long as possible.

Washington's search for a quarterback will create more headlines. But Washington knows well that how it handles contracts this offseason will help determine what can be done in the future with its defensive line.

After all, Washington's optimism lies as much in that front as anything.

"The defensive line play is the engine that drives this team," said new Washington general manager Martin Mayhew, "that drives this defense at least."

There's a reason Washington ranked second in yards allowed per game and fourth in points, as well as fourth in sacks per pass attempt. That's why the team went 7-9 in winning the NFC East.

"The defensive front is one of my favorite defensive fronts in football," ESPN NFL analyst Matt Bowen said. "They have players that are impact players."

That front includes five first-round draft picks, though one of them -- defensive end Ryan Kerrigan -- will be an unrestricted free agent. Because he still wants to start and would only be a backup in Washington, it's hard to imagine him returning. But that still leaves four first-round picks, all of whom have performed well, and will command big contracts in coming years. All are under contract for 2021.

The good news is Washington hit on its first-round picks.

"They're not going to be able to keep all those guys," one league source said.

"They will have to be judicious in which ones they keep," said salary-cap expert Joel Corry, who is a former agent who works for CBS Sports and hosts a podcast devoted to salary-cap issues.

Washington's plan could start this offseason with tackle Jonathan Allen, who would like an extension rather than playing on the fifth-year option in 2021. There hasn't been movement on a deal, though some of that stems from teams still not knowing the salary-cap ceiling.

Also, as one league source said, Washington must first figure out its quarterback situation and how much money will be allocated before moving on to bigger deals. Allen's side could wait to see what free-agent tackle Leonard Williams receives as well.

Washington coach Ron Rivera values building the lines and, therefore, keeping them together as long as possible. Rivera has mentioned both lines needing to be the team's foundation. He's not alone in that thinking.

"I'm a big believer that you start building defenses from the front back," said Washington's new senior vice president of player personnel Marty Hurney. "If quarterbacks don't have time to throw the ball it makes it a lot easier on the back end."

But when it comes to roster building, Corry said, Washington needs to "look to San Francisco as a bit of a model."

Indeed, the 49ers accrued comparable line talent, building a defensive line using first-round picks on Arik Armstead, DeForest Buckner, Solomon Thomas and Nick Bosa. They also added Dee Ford in free agency. Last offseason, they traded Buckner, entering his option year and with Armstead a free agent, to Indianapolis for a first-round pick. They then re-signed Armstead.

The 49ers also have to plan for Bosa's eventual free agency, just like Washington will have to worry about defensive ends Montez Sweat and, especially, Chase Young in the future. As of now, Khalil Mack has the highest per-year average of pass-rushing ends at $23.5 million, but that was signed in 2018 before the season started. Bosa, if he stays healthy, will re-set the market when he's up to get paid, followed by Young a year later.

"Whatever Bosa gets is Chase Young's floor," Corry said. "I anticipate Bosa will be over $30 million a year when the time comes."

The difficult part for Washington will be deciding who it must part with and when. Allen will provide a test as he's someone who is a respected voice in Washington's building. He also ranked seventh among tackles in the NFL last season with a 13.3% pass rush win rate, according to ESPN Stats & Information.

Do you let a player like Allen leave? Then again: Will they want to pay him around $17 million per year? Washington could also use the franchise tag on him next season.

Also, Washington has two other players who can play Allen's spot in backup Tim Settle, a free agent after 2021, and Matt Ioannidis, who has two years left on an affordable deal. Ioannidis led the interior linemen with a combined 16 sacks in 2018 and '19 and had 1.5 in three games before getting hurt this past season.

Meanwhile, Daron Payne plays more over the center and ranked ninth among interior linemen with a run stop win rate of 38%. But he was second among all linemen with 44 stops when double teamed. Payne, the 2018 first-round pick, will enter his option year in 2022 and also would command a high price. The following year it would be Sweat. And the year after that Young.

Rivera said when he coached in Carolina, the staff studied the impact of the interior pass rush.

"It was very important," Rivera said. "When you couple those with guys that can come off the edge, the quarterback can't step up, and it creates something. It meant a lot of good things for the rest of your team whether it's getting sacks, creating takeaways, creating interceptions."

Washington can bring this group back in 2021. But at some point, decisions will have to be made.

"If you keep all those guys in the middle," said one executive, "then you'll lose one of those edge ones."