Ty Nsekhe, here playing in Trent Williams’s place during the 2015 season finale at Dallas, will likely step in for him for the next four games. (Ronald Martinez/Getty Images)

The Washington Redskins (4-3-1, 2-1) return to FedEx Field to launch the second half of their season Sunday against the Minnesota Vikings (5-3). Neither team has won since Week 5. Washington has had a loss, a tie and a bye week since then, while the Vikings have lost their last three. Both teams’ playoff hopes depend on reversing that trend.

Here are five storylines to follow:

1. Setting a new tone: It has been four weeks since the Redskins won. Since Oct. 16, they have been their own worst enemy, squandering a winnable game at Detroit, then crossing the Atlantic only to play the Cincinnati Bengals to a 27-27 tie, failing to capitalize on multiple opportunities for a victory. After rebounding from a poor start to reach 4-2, with a shot at the division lead within reach, the Redskins have since looked like pretenders rather than the reigning NFC East champions. The bye gave players a chance to heal and coaches a chance to fix the most glaring woes: offensive futility in the red zone and defensive anemia on third down. Will Sunday set a new tone?

2. Ty Nsekhe tackles Trent Williams’ role at LT: It’s the first of four games the Redskins will be without Pro Bowl left tackle Trent Williams, who’s serving a four-

Josh Norman. (Al Bello/Getty Images)

game suspension for multiple violations of the substance-abuse policy. Journeyman Ty Nsekhe will fill the breach. At 6-foot 8 and 335 pounds, Nsekhe is a massive presence. General Manager Scot McCloughan insists that the swing tackle, who has played a role in all eight games, would be a starter on many NFL teams. And Coach Jay Gruden has voiced confidence. Nsekhe draws a tough assignment Sunday, squaring off against Vikings right defensive end Everson Griffen, who boasts a team-high six sacks.

3. Managing turnovers: The Vikings may be on a three-game skid, but there’s no mistaking their strength: defense, front to back. They’re allowing the fewest points in the NFL (15.8) and third-fewest yards per game (298.9). But they could inflict the most damage on takeaways. The Vikings are plus-12; the Redskins’ giveaway/takeaway ratio is zero. The Vikings defense has 10 interceptions, with seven players accounting for the total. So quarterback Kirk Cousins (12 touchdowns, seven interceptions) must be precise with his accuracy, timing and decision-making. And when Vikings quarterback Sam Bradford is under center, the Redskins secondary needs to do more than bat down passes. It’s time for CB Josh Norman to turn broken passes into interceptions.

4. Change at running back: Gruden finally ran out of patience with Matt Jones’

inability to hang onto the football and sat him. This week, he announced that Rob Kelley, the undrafted rookie from Tulane, would start Sunday. If Jones is ruled a healthy scratch, as is possible, it will mark a significant setback for the third-round

Sam Bradford. (Photo by Elsa/Getty Images)

pick in 2015, whose apparent promise was the reason Alfred Morris was allowed to depart. For now, the 6-0, 228-pound Kelley has coaches’ confidence. They like his toughness, physicality and maturity. “Nothing is too big for him,” offensive coordinator Sean McVay said. “We expect to see him just improve as the season goes along.”

5. QB Sam Bradford and a Vikings offense in flux: The mid-season resignation of Vikings offensive coordinator Norv Turner caught everyone by surprise. It also threw a slight wrinkle in the Redskins’ defensive game-planning. But regardless of who’s calling the Vikings’ offensive plays, it’s clear the Redskins secondary must respect the ability of wide receiver Stefon Diggs (48 catches, 546 yards and two touchdown), the Maryland and Good Counsel product who’s looking forward to a personal homecoming. Though the Vikings offense is among the NFL’s least efficient, Bradford has been better than expected since being acquired in a trade. He has thrown just one interception and has a 99.0 passer rating.