Marc Trestman's offense does a lot to try and dictate favorable matchups. One way it does this is using Brandon Marshall extensively in the slot. When people think of slot receivers, they tend to envision the Wes Welker, Jeremy Kerley prototype. You think of the guy who isn't big or fast enough to live on the outside but possessing the requisite short area burst to create separation over the middle and make plays after the catch. There will always be a spot for this type of player, but these days seeing a primary receiving target in the slot is more and more commonplace.
Less talented cover cornerbacks and safeties typically line up there so it is a chance to create a potential mismatch. If you counter by having one of your top corners there, you take that corner out of his comfort zone by working him in the middle of the field without the boundary to help him that he normally has.
Marshall actually has over half his snaps from the slot this season. It's not hard to imagine the challenge this might present when the Jets stick Kyle Wilson in the slot. Wilson is giving up six inches, which will make it easy for Jay Cutler to target Marshall and let his guy go get it. The Jets have also utilized Dawan Landry rather frequently in the slot in the first two weeks. That also doesn't sound like a terribly favorable matchup for the Jets.
This is yet another challenge the Chicago offense presents. Without knowing whether Marshall will end up on the outside makes it more difficult to figure out where to send the coverage. Rolling the coverage to an outside receiver might give the Bears a big edge if Marshall is actually in the slot.