By Dan Durkin-

(CBS) Through six games, it’s not a mystery to figure out who the Bears are going to try and get the ball to in the passing game.

In fact, 88 percent of the team’s receptions have been made by Matt Forte, Martellus Bennett, Alshon Jeffery and Brandon Marshall. When I asked coach Marc Trestman what they were trying to do to get other players involved, he told us plainly, “We’re really not.”

And he wasn’t lying.

Last week against the Falcons, quarterback Jay Cutler’s 381 passing yards were his most since joining the Bears. Literally, 99 percent of those yards went to the Bears’ main quartet, with the only completion to someone else being a three-yard touchdown pass to Josh Morgan.

So, if it’s so obvious who the Bears are going to throw the ball to, how is Trestman able to continually find ways to get the ball into the hands of these four players? Formations and scheme.

Heading into Atlanta, the Bears were short on explosive plays (passes of 18 or more yards). Given the physical mismatch the Bears’ receivers pose, teams have shied away from man coverage. Instead, they’ve opted for zone coverage to keep a top on the defense and force the Bears to string together a long series of completions and meticulously work the ball down the field.

Against the Falcons, the Bears hit on four explosive plays, two of them coming from the same scheme — trips bunch verticals.

The Bears ran this scheme successfully against both man and zone coverage. So, let’s step inside the film room to take a look at what the Bears did and how they varied it based on the coverage that was presented.

At the 7:04 mark of the second quarter, the Bears broke the huddle in their preferred 11 personnel grouping in a 3-by-1 far trips right formation. The Falcons responded with nickel personnel in a 3-3-5 alignment.

Marshall is lined up as the flanker (Z) and goes in “zip” motion to the bunched set. This motion is to give the Bears a man/zone presnap recognition. The Falcons’ secondary shifts, so the Bears know they have man coverage at the snap of the ball.

The Bears run a three verticals combination from the trips bunch, as Santonio Holmes — the split end or “X” receiver — runs a shallow crossing route. Jeffery runs a vertical to clear out, and Marshall and Bennett switch their releases and angle their routes toward the sideline on the opposite side of the field.

The Falcons’ two high safeties play a hybrid coverage. At the intersection of the routes by Holmes and Marshall, the Falcons use a “banjo” technique and exchange coverage responsibilities. Safety Dezmen Southward drives down to pick up Holmes, and cornerback Robert Alford picks up Marshall. It’s at this point that Marshall gains a step and stacks on top of Alford.

Meanwhile, Cutler gets flushed slightly to his left, but he keeps his eyes down the field and drops a perfect pass over the top to Marshall for a 47-yard completion.

The Bears dialed this scheme up again on the last play of the third quarter, again on third down. This time the Falcons used dime personnel in a 4-1-6 alignment in a single-high safety look.

Receivers are taught to keep running when they’re facing man coverage. However, against zone, they’re taught to stop their routes and settle into the voids.

The Falcons changed their coverage entirely this time, running a zone Cover-3 robber, in which safety Kemal Ishmael cuts down on Marshall’s route over the middle.

Bennett and Marshall again switch their releases and run deep curls as Jeffery runs a deep out route to hold two defenders.

Cutler makes a quick — and correct — decision to hit Bennett up the seam for a 26-yard gain.

This is an example of how Trestman schemes plays with in-route sight adjustments, which enables receivers to let the coverage dictate the shape of their route at the top of the stem. This was an identical scheme run from the same formation against different coverages, yet both yielded explosive results.

Dan Durkin covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter at @djdurkin.