Days after trading away their top outside cornerback, the Washington Redskins added a low-risk, high-reward depth option in former Eagle Ronald Darby. The team agreed with Darby on a one-year deal worth $4 million, according to a person with knowledge of the situation.

The 26-year-old was a solid starter for the Buffalo Bills and the Eagles in the past five seasons, when healthy, and he strengthens the Redskins’ cornerback competition. The team traded disgruntled top corner Quinton Dunbar to the Seattle Seahawks for a fifth-round pick last week, and Darby figures to have a chance to earn one of the team’s starting jobs at outside cornerback.

The Bills drafted Darby out of Florida State in the second round in 2015, and he became one of the league’s best defensive rookies. During training camp in 2017, the Eagles traded wide receiver Jordan Matthews and a third-round draft pick for him.

The Eagles had lofty expectations for Darby, and when he was on the field, he at times fulfilled them during his three seasons with Philadelphia. He intercepted six passes, defensed 32, and helped hold off the New England Patriots to win Super Bowl LII. But more often, he struggled — like Week 1 last season, when Redskins rookie wide receiver Terry McLaurin recorded five catches for 125 yards and one touchdown while primarily lining up opposite Darby — or battled injuries to his right ankle, right knee, and hip. Darby sat out nearly as many games (20) as he played (28).

In 2019, he signed a one-year contract with the Eagles for $8.5 million. Despite missing five games in the middle of the season with the hip injury, he started 11 games with serviceable results. Darby didn’t find as robust a market this year, perhaps because of a deep draft class of cornerbacks, so for the Redskins, he’s a value add, making slightly more than what Dunbar would have earned this season ($3.5 million).

Washington’s top cornerback is expected to be Kendall Fuller, who signed a four-year, $40 million contract this offseason. Fuller played mostly the slot corner position in Kansas City, and he can play on the outside. The No. 2 starter alongside Fuller could be a competition between Darby and Fabian Moreau, the promising 25-year-old who replaced Josh Norman in the starting lineup late last season.

Behind the trio of Fuller, Moreau, and Darby, the Redskins have four 24-year-olds hungry for roster spots themselves: Danny Johnson, Greg Stroman, Jimmy Moreland, and Jeremy Reaves.