McKnight of course is the Jets special teams standout and had lost out as the team's third-down back role to Bilal Powell in the preseason. When McKnight was recruited at the college level, some coaches wanted him to play defensive back, and according to Sporting News, he might have been great.
... several coaches recruiting McKnight (namely Ole Miss, according to Bruce Feldman’s book, “Meat Market”) thought McKnight could have been a Pro Bowl cornerback if he stayed on the defensive side of the ball.So while McKnight might have the raw skills to play corner, it's not as if he's done much of it ... so how could this work for the Jets?
He's probably going to struggle against front-line receivers, so if he's going to drop in coverage, then look for him to cover a player like Emmanuel Sanders instead of someone like Wallace, Brown or Cotchery since they might best him with extremely disciplined route-running. McKnight could be used as a zone player, but that also might invite some miscommunications, so as GGN notes, while he might see some time in coverage, he might be best used as a blitzer.