From Comcast SportsNetFLORHAM PARK, N.J. (AP) -- Joe McKnight walked into the Jets' offensive meeting room and Rex Ryan broke the news to the backup running back."He said I've been traded," McKnight recalled Wednesday. "I was traded to the defense."McKnight will start working "a ton" at cornerback to help offset the loss of All-Pro Darrelle Revis, who's likely out for the season with a knee injury. McKnight, whose role on offense has been limited this season, played the position in high school and practiced at cornerback in Week 2 when Revis was sidelined by a concussion.Still, finding out about his new role on Monday wasn't exactly an exciting moment for McKnight."I mean, I was drafted as a running back," the former Southern California star said. "The way I took it as was I wasn't good enough to play running back. I don't know if that's the case or not, but that's the way I'm looking at it right now."McKnight didn't ask Ryan if that was the situation, and insisted he's not disappointed. After all, it could mean getting on the field a lot more after carrying the ball just three times for 14 yards in three games."I kind of get tired of just standing on the sideline watching," McKnight said. "I'm just happy to play right now."McKnight practiced on defense Wednesday, wearing a green No. 25 jersey instead of the offense's usual white, and intercepted Mark Sanchez, Tim Tebow and Greg McElroy once each."He'll have a role on offense, but we're also teaching him to play corner in almost, not quite a full-time capacity, but he's going to be over there a ton -- in the meetings and everything else," Ryan said.Ryan first mentioned the idea of using McKnight in the secondary in the running back's rookie season in 2010. McKnight, who's also the team's primary kickoff returner, even got into New York's game at Baltimore last season on defense as a blitzing defensive back who forced Joe Flacco into throwing an interception."He's a guy we saw on scout team as a rookie that he has the necessary skills to be able to play corner," Ryan said. "He's got the speed, the size, the athleticism, the ball skills -- everything you look for in a corner. ... I definitely would not bet against Joe McKnight becoming a good corner."Revis tore the anterior cruciate ligament in his left knee at Miami on Sunday, and will be replaced by Kyle Wilson as a starter. While the Jets also have Ellis Lankster and Isaiah Trufant as backups, the athletic McKnight gives Ryan another option in the secondary.McKnight was actually an outstanding cornerback in high school in Louisiana, returning three picks for touchdowns in his junior season."It's been a while since I've played cornerback," he said. "Maybe if I would've played it four years in college, that would've helped. But me playing cornerback in high school doesn't help me right now. I've got to work on some things."He was even better as a running back back then, with his speed and shiftiness making him a top recruit after his senior year. After an up-and-down career at USC, the Jets drafted him in the fourth round in 2010 -- but he hasn't yet made the impact on offense that was expected. Instead, New York is hoping McKnight can help make up for the loss of arguably the league's top defensive player.And that might start Sunday, when the Jets take on the San Francisco 49ers."Hey, they can go ahead and do it," McKnight said. "I'm ready for it. If they want to come throw to my side, I can easily show them I can play."