ORCHARD PARK, N.Y. -- Last season, starting cornerbacks Stephon Gilmore and Ronald Darby were the strength of coach Rex Ryan's otherwise uninspiring Buffalo Bills' defense. This season, both Gilmore and Darby have both become question marks.
The latest chapter in the two players' tumultuous season came during a Nov. 7 loss to the Seattle Seahawks, when Darby was benched in the first half in favor of veteran Corey White. As the Bills returned from their bye week Monday, White told reporters that coaches have opened a competition between him and Darby for that spot, and that the two split reps in practice.
The decision -- and it's initially unclear whether it was by Ryan, defensive coordinator Dennis Thurman or defensive backs coach Tim McDonald -- represents a considerable fall for Darby. The Bills' 2015 second-round pick finished second last season in the Associated Press' Defensive Rookie of the Year voting, behind Kansas City's Marcus Peters, and was tied for seventh in the NFL with 14 passes defensed.
Sitting stoically at his locker Monday, the typically reticent Darby took a measured approach to the development that his starting job might be in jeopardy this Sunday when the Bills travel to play the Cincinnati Bengals.
"It is what it is, at the end of the day," he said. "I'm not sure what the coaches [are thinking]. I just go out there and play."
Graded by Pro Football Focus as the NFL's ninth-best cornerback last season, Darby has slipped to 62nd in the same ranking this season. His counterpart, Gilmore, has dropped from 14th in 2015 to 91st this season, leaving Ryan searching for answers about why one of his top defensive players hasn't performed as expected.
"It's been up and down. Y'all see it," Darby said of how the two are playing this season. "At the end of the day, plays are gonna get made on you. Like, it's the NFL. They getting paid, too. So it [could] be technique, for the most part. It's always gonna be the [defensive back]'s fault. At the end of the day, you just got to be able to step up and make a play.
"Anybody can start playing bad or give up a play at any time. It's the position. [Defensive back] is one of the hardest positions on the field."
Ryan came to Darby's defense after the loss to Seattle, saying that his cornerback felt sick before the game and that Ryan made a mistake in playing him as much as he did. Darby downplayed his illness in speaking to reporters Monday, saying he his body was "straight" for the game.
During Monday's practice, Darby had an extended one-on-one chat on the sideline with McDonald while the rest of his teammates were involved in a drill, including White in Darby's place with the first-team defense. However, Darby said after practice that the conversation, "wasn't as deep as it seemed. We were just over there talking."
McDonald, a six-time Pro Bowl safety for the Cardinals and 49ers in the late 1980s and early 1990s, has taken a closer role with the Bills' cornerbacks this season after focusing more on the team's safeties last season. Donnie Henderson, who served as co-defensive backs coach last season and worked with Darby and Gilmore, was not retained after last season.
Darby praised McDonald and assistant defensive backs coach Ed Reed and put his struggles on himself.
"It's frustrating," he said Monday. "I've been up and down. But at the end of the day, I'm young. I'm gonna learn from my mistakes. I'm just gonna get better. I've been through rough times before. It ain't nothing new."