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ENGLEWOOD, Colo. --** Andrew Luck's mobility passes under the radar, compared to the second-year quarterback's other array of strengths. But his ability to ease away from the pass rush and be a steady, effective scrambler offers a dimension that the Broncos defense must take into account Sunday.

"Any time you have a quarterback with mobility you obviously want to make sure that you have a plan to keep him corralled -- (to) not let him get too comfortable but still make sure that if he does decide to run that you have a way to get him down," said Broncos defensive coordinator Jack Del Rio. "We've got different things that we'll look at and hopefully execute well and help slow him down."

Only seven quarterbacks around the league this year are more likely to keep the football and take off than Luck, who runs once every 9.3 times he's directly involved in the play (sack, passing attempt, carry). His per-carry average is a solid 6.4 yards -- not in the realm of the explosive scramblers around the league, but given that he would rather take a prudent slide for the safety of himself and the offense rather than run into contact, this isn't a detriment.

"He's broken a lot of tackles back there; he's definitely hard to get down," said Broncos linebacker Von Miller. "They do a lot of stuff to try to confuse defenses."

Much of that stems from Luck, who is effective dropping back, working from a shotgun, rolling out or staying in the pocket. Within the passing game, the Colts change up their tactics as much by moving the pocket and using misdirection as they do with their personnel packages.

The shifts put a burden on the Colts' offensive line, which is something of a transition phase this year, featuring a pair of new starters: free-agent pickup Gosder Cherilus at right tackle and rookie Hugh Thornton at left guard (he also started at right guard in Week 1). 

Cherilus, the replacement for current Broncos backup Winston Justice, has been steady at his spot, but Thornton has endured typical rookie ups and downs. I charted Thornton with six pressures allowed the last three games, including two last week, a number that ProFootballFocus.com also calculated. 

The Broncos have successfully used stunts to generate pressure through the last six games, and even with Miller back from his six-game suspension, there's no reason to change that tactic. If they successfully use this, then they could attack Thornton, and might set Malik Jackson up for more sack opportunities, allowing him to sustain the momentum from his three-sacks-in-two-games burst the last fortnight.

But pressure must also be combined with a focus on containment and perhaps forcing Luck to settle for incompletions, rather than moderate gains. That's the difference between second-and-10 or second-and-4, and this is where the Colts have used Luck's mobility to their advantage; it keeps them out of desperate situations with limited playbook options.

NOTES:

-- Like Manning, Luck isn't afraid to force a throw when he feels his receiver has the upper hand. His 29-yard touchdown pass to T.Y. Hilton against the Seahawks in Week 5 was evidence of this; a quick glance to his left as he set up before the snap allowed him to see Seattle safety Brandon Browner in one-on-one coverage against wide receiver T.Y. Hilton. Hilton didn't have separation from Browner when Luck stepped back and threw to a spot, but his quick read gave him faith to know that Hilton was going to capitalize in that situation against an out-of-position Browner.

-- According to ProFootballFocus.com, the Colts have allowed one quarterback pressure (hurry) every 3.48 pass plays. This is the ninth-worst ratio in the league. (By comparison, Denver allows one hurry every 7.29 pass plays; this is the best in the league.)

-- Watch for the presence of fullback Stanley Havili. When he's in the game, the Colts run 57.4 percent of the time, averaging 3.86 yards per carry. They're more effective running without Havili on a per-carry basis, averaging 5.30 yards per rush when he's not in the game, but are less likely to run, keeping it on the ground just 39.0 percent of the time without their fullback on the field.