Linemen stick out like red-nosed reindeer when the offense is stuck in neutral, as has been the case with the Broncos much of this season.

For the Broncos’ big boys up front, most of the attention focused their way has been negative, due to a sporadic running game and porous pass protection.

Now, quarterback Brock Osweiler is getting ready to make his first career start Sunday against Chicago, replacing the injured Peyton Manning. For the offense to come out of its slump, the play of the offensive line will be key.

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“There should be a sense of urgency and not a sense of panic,” guard Evan Mathis said. “We need to do a better job in protection.”

Having a more mobile quarterback such as Osweiler could also help. Manning and Osweiler were sacked a combined five times last Sunday against Kansas City, and Manning threw four interceptions before being benched.

It hasn’t just been up to the starting five to protect the quarterback, either. Coach Gary Kubiak has implemented a heavy rotation system trying to both develop depth and keep veterans fresh.

Reserve guard Max Garcia played 42 of 71 snaps Sunday against the Chiefs, relieving both Mathis at left guard and right guard Louis Vasquez. “Swing” tackle Tyler Polumbus played 20 snaps in place of left tackle Ryan Harris. Among the offensive line, only center Matt Paradis and right tackle Michael Schofield played every snap.

After 10 weeks, though, it’s clear the offensive line has not gelled. The Broncos are coming off back-to-back losses during which they were unable to generate a running game.

“We need to just take ownership of our assignments individually and just get that done,” Garcia said. “We don’t have any room for excuses right now at this point.”

The line also has a new challenge on Sunday, blocking for Osweiler, who has more mobility than Manning, and a stronger arm, but is making his first NFL start.

Kubiak and offensive coordinator Rick Dennison keep insisting the playbook won’t change much. Running back C.J. Anderson said the only difference is that “everything is under center” which means Osweiler would not work out of the shotgun formation much, as Manning has.

The expectation is that Kubiak will call plays to emphasis Osweiler’s strengths, such as more bootlegs and play action. That could help open up the running attack.

Kubiak told Osweiler to avoid some of those unnecessary hits like the one he took on the two-point conversion scramble against the Chiefs.

Mathis has blocked for quarterbacks ranging from Michael Vick to Nick Foles and he said a quarterback’s mobility rarely changes how he finishes his blocks, perhaps only three or four times a game.

If Osweiler is to jolt a sluggish offense to life, he’ll need his big guys in front of him to help pave the way.

Cameron Wolfe: 303-954-1891, cwolfe@denverpost.com or @CameronWolfe