By Dan Durkin-

(CBS) The second level of the Bears’ defense has been hit hard by injuries.

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Chicago linebackers Lance Briggs (ribs), Jon Bostic (back), Shea McClellin (hand) and D.J. Williams (neck) all sat out Wednesday’s practice ahead of Sunday’s game at Atlanta.

On the field, the Bears’ starting linebackers were Khaseem Green at Will, Darryl Sharpton at Mike and Christian Jones at Sam.

Other Bears to sit out were offensive tackle Jermon Bushrod (knee/ankle), safety Ahmad Dixon (hamstring) and center/guard Taylor Boggs (hamstring).

Running back Matt Forte also sat out, but that was listed as a coaches’ decision.

On a positive note, center Roberto Garza (ankle) was a full practrice participant.

Here’s the rest of the injury report from Wednesday:

Limited
— S Chris Conte (concussion)
— DT Jeremiah Ratliff (concussion)
— CB Sherrick McManis (quad)

Blindside block calls affecting coaching

The Bears were flagged for two blindside blocks during Sunday’s loss against the Panthers. One was called on Sharpton, wiping out a 27-yard punt return.

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The NFL rulebook states that it’s an illegal blindside block “if the initial force of the contact by a blocker’s helmet (including facemask), forearm or shoulder is to the head or neck area of an opponent when the blocker is moving toward his own end line and approaches his opponent from behind or from the side.”

That clearly didn’t happen on either call against the Bears, and Mike Pereria of Fox Sports disputed both calls in this video breakdown.

Bears special teams coach Joe DeCamillis adamantly disagreed with the call on Sharpton and said both plays were sent to the league for explanation. In the meantime, such calls are affecting how blocking techniques are taught on the field.

“It’s already changed a lot of things,” DeCamillis said. “We try to manage that a different way than we used to. You used to give points out for that, those de-cleaters and all that stuff. And that one wasn’t even close to being a de-cleater. It’s how they get off the ground, he didn’t move, it wasn’t towards the head or anything like that.”

Shuffling the secondary

Isaiah Frey went from the Bears’ starting nickel cornerback against the Panthers to the waiver wire yesterday. The Bears made a corresponding move to activate Al Louis-Jean, but he wasn’t one of the three players coach Marc Trestman mentioned as being in the mix for the role.

That will be between McManis, Brock Vereen and Demontre Hurst.

“We’re processing through that,” Trestman said. “Sherrick’s availability will be a part of that, Brock’s capabilities will be a part of that. We’ll move guys around through the week. We’ve got a plan for that from a competitive standpoint to be at our best in that regard. So we are moving some people around. D-Hurst is involved in that process as well.”

The Falcons have the league’s second-best passing game and heavily utilize three-receiver personnel groupings and their slot receivers, so this is a situation to monitor for the rest of the week.

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