Redskins.com's Stephen Czarda provides five things we've learned about the Washington Redskins in games in Weeks 10-13 -- Vikings, Saints, Giants and Cowboys -- of the 2017 regular season.

1. While the Redskins have returned Trent Williams to the lineup, the offensive line depth still faces weekly challenges.  
As has been the case over the second half of the season so far, the Redskins have entered games with different starting offensive line combinations seemingly every week.

Against the Minnesota Vikings in Week 10, the Redskins had their entire offensive line active including center Spencer Long, although the fourth-year Nebraska product did not start and appeared on 12 offensive plays, and a returning Ty Nsekhe off a core muscle injury that sidelined him for five games.

That would be the last time Washington had the entire offensive line active, though, as Long and starting left guard Shawn Lauvao have since been placed on Injured Reserve. Rookie center Chase Roullier, the No. 2 center going into the season, has missed the last two games with a hand injury while Williams has been in and out of the lineup as he continues to battle a painful knee injury.

Starting right tackle Morgan Moses was also carted off last Thursday against the Dallas Cowboys after just 16 offensive plays.

While the Redskins are hopeful that Roullier can return this week, the team will have to determine over the final four games just how much Williams plays. Redskins head coach Jay Gruden said that the team – and quarterback Kirk Cousins in particular – needs him, but they also have to think about his long-term health.

"I think the big thing is the timeline," Gruden said. "Let's find out what the timeline is for the surgery if he has to have surgery, No. 1 – what type of surgery it's going to be and how long it's going to put him out.  We'll take all those and then figure out what we're going to do with him. If he's good enough to finish the season, he will finish out the season."

If he can keep playing and Moses is also healthy enough to suit up, Washington may finally get an extended look at Nsekhe at left guard.

While the 32-year-old started at guard against the Cowboys, he had to shift over to right tackle to replace the injured Moses. He also played one snap at left tackle.

"I think moving forward, we'll try to get him in a spot where he can play and focus and play that spot," Gruden said. "Unfortunately, he's had to play all three – left guard, left tackle and right tackle. It's easier said than done for these guys. It's a different stance. It's a different technique.  It's just totally different to be a left guard, left tackle, and then all of a sudden play right tackle. So, naturally he's going to have some plays where he struggles, but for the most part, he played OK from time to time."

2. Quietly on pace for another double-digit sack season, Ryan Kerrigan joins elite company.  
It was a special Thanksgiving for Kerrigan, as his dominant first half performance against the New York Giants put him in rarefied air.

Entering the game with seven sacks after tallying one against New Orleans Saints quarterback Drew Brees four days prior, Kerrigan took down Eli Manning early in the first quarter for his eighth sack of the season.

In the process, Kerrigan joined Jared Allen, Derrick Thomas, DeMarcus Ware and Reggie White as the only players in NFL history to record at least 7.5 sacks in each of the first seven seasons of a career since the NFL adopted sacks as an official statistic in 1982.

Then on the first play of the second quarter, Kerrigan once again sacked Manning, this time on a 3rd-and-7 play from Washington's 33-yard line that pushed New York out of field goal range.

"That's pretty cool, pretty cool and obviously some pretty cool names, those are some pretty good pass rushers," Kerrigan said. "And [to] have that company in some way is pretty cool."

While Kerrigan isn't as colorful a personality in front of the camera like some of his pass rusher counterparts across the league, his presence in the Redskins' locker room helps a young unit.

"You're just so impressed with not only what he is as a football player but as a person and how he conducts himself on and off the field," Gruden said. "He's always available, he's practicing every day, he's playing hard every day, he consistently has a high motor every week and, you know, he's just a great captain, great leader – not a captain, but a great role model for these young guys coming up and preparing themselves to be great NFL players – you can't have enough Ryan Kerrigans on your team."

3. Samaje Perine gets his opportunity to take on the lead-back role.  
After Rob Kelley's knee and ankle injuries in the first half of Washington's Week 10 game against the Vikings resulted in his placement on Injured Reserve, Perine was thrusted into the starting running back role.

The 2017 fourth-round pick out of Oklahoma entered the season with high hopes, but had just 66 carries for 210 yards (3.2 yards per carry) with no rushing scores through the first nine games of the season.

Despite the limited success as a backup to Kelley, Perine flourished the next two weeks with back-to-back 100-yard performances. It was the first time a Redskins running back collected consecutive 100-yard performances since Alfred Morris did so in Weeks 9-10 of the 2013 season.

"I've liked the fact that after his 10th carry he's better than his first carry, and his 12th carry he's better than his 10th carry," Gruden said. "He just continues to get better and better, his vision has been good and his decisiveness has been outstanding."  

Perine's improvement comes with more reps in formations outside of the shotgun, which is what he mostly ran out of during his days at Oklahoma.

"Everything is right there extremely quick," Perine said. "Like in the gun, you have an opportunity. ...It's just the reps. You just have to get the reps and once the reps build up and once you get more comfortable in the situation, then things start to slow down for you and once you get comfortable in the offense, you know where everyone is going to be so you can anticipate what the line is doing, what the defense is doing, and you just go from there."

Amongst rookie running backs, Perine is now fifth in rushing yards (465).

4. Despite three losses in the last four weeks, D.J. Swearinger continues to show leadership and standout play on the field.
While the Redskins haven't been able to replicate their early season defensive success over the last few weeks, Swearinger remains one of the most impactful defensive backs in the NFL.

Starting in the second quarter and then extending through most of the third quarter in Week 10, the Vikings' offense was having its way against the Redskins, scoring touchdowns on four consecutive drives.

They looked poised to strike again late in the third quarter before Swearinger came down with an interception on Case Keenum. Then on Keenum's next throw in the fourth quarter, Swearinger once again picked him off.

It was the first multi-interception game of his career.

"In the second half, it was good to see [the defense] come out with a little more energy and see D.J. make those two plays and show the type of leader he is," Gruden said.

Swearinger would record a third interception in as many quarters in the opening frame against the Saints, picking off Brees on New Orleans' opening drive in Week 11.

But his impact has extended past just racking up interceptions, as the 26-year-old has keep the communication flowing through the defense despite inside linebackers Mason Foster and Will Compton both being placed on Injured Reserve, replaced in the lineup by Zach Vigil and Josh Harvey-Clemons.

"I can be a lot of help with being down in the box, moving guys over," Swearinger said. "If it's man-to-man, telling guys, 'You've got this guy, you've got that guy.' I can be a lot of help and I definitely, definitely need to be a lot of help with the guys coming in."

5. Displaying gutsy performances, Kirk Cousins has kept the offense afloat despite constant change around him.
Cousins is one of only three starters on the offensive side of the ball to start every game for the Redskins this season, joined by Moses and tight end Vernon Davis.

The offensive line situation in front of Cousins, of course, has been fluid while he's lost both Kelley and breakout star Chris Thompson to Injured Reserve over the last month. Pro Bowl tight end Jordan Reed has also missed Washington's last five games.

Despite all of the constant change around him, Cousins has continued to be effective over the last four games, completing 93-of-145 passes for 1,142 yards with 10 total touchdowns.

Gruden believes that Cousins' continued success is due to the way he approaches the game.

"He's very focused on his job," Gruden said. "That's what you have to be as a quarterback. You have to go through your progressions and you have to worry about what the defense is doing and count on the fact that the players around you are going to do their job. And that's the way it is around here, that's what we try to preach every day to do your job. And Kirk's doing an excellent job of staying in his lane, helping out the receivers or making some adjustments need be, but for the most part, he's just worried about his job and what the defense is doing and what they're giving to him."

And with new players around him, Cousins has to be more of a leader, both in the huddle and in team meetings.

"Two years ago, I'm a first-year starter playing with very experienced receivers, Pro Bowl-type receivers, and that's a different dynamic than being now in my third year starting and working with younger players," Cousins said. "I enjoy that opportunity to communicate and lead and teach and share experience. It's hard to help coach on the field if you haven't been there before and learned from already having been out there. I'm just going to draw on my previous experiences as a young player and try to impart that to the guys around me – if they need it. A lot of them don't, but I'll speak up when necessary and enjoy that opportunity and that part of quarterbacking."