SANTA CLARA, Calif. (AP) For all the wrinkles and formations in Kyle Shanahan's new offense as San Francisco 49ers coach, there is one aspect that might be most important.
As one of the league's biggest proponents of play-action passes out of the same formations as his base run plays, Shanahan's philosophy is to make the defense commit to stopping the run or pass and then beat the defenders by running the opposite.
By making run plays look like passes and passes like runs, Shanahan wants to make the defense react a step late crashing against the run even on a handoff or dropping back in coverage on a pass.
''If it looks the exact same and that guy does what he does to make a zero-yard run, but he also has to get under a 15-yard route, that puts that guy in a bind,'' Shanahan said. ''If he's stopping the run, it's going to help out the receiver and the quarterback. If he's not stopping the run because he's so worried about the receiver and quarterback, now you're getting 4 yards before that guy shows up. It makes people hesitate. If you let a defense tee off in this league, they're usually going to get after you once you become one-dimensional.''
Teaching play action has been one of the keys so far this offseason for the 49ers. While much is made of the ability of a quarterback and running back to sell the play fake and make the defense hesitate, most of the defenders use the offensive line as their key to what play is being run.
So Shanahan runs a lot of his play action out of the same looks that make up the bulk of his running game with the outside zone runs. The linemen start the play blocking the same way they do on a run, putting the defenders in a bind that the quarterback can then exploit as soon as he pulls the ball back from the running back.
''When the offensive line comes off like it's the run, you can see times where we watch the film and the linebackers are reacting to them,'' 49ers quarterback Brian Hoyer said. ''They're not even looking at us. They're looking at the offensive line's intention, the fullback, the tight end. We've just got to do the end part of it.''
Denver linebacker Brandon Marshall said it takes the entire offense working in sync to pull off the fake properly, from the running back going full speed as if he's getting the ball to the quarterback hiding the ball. Marshall said former teammate Peyton Manning was the best he's seen at that.
But the most important aspect is the offensive line.
''They can't fire out,'' Marshall said. ''It's really a pass block. But it's really the fake. I think that's what it is. Because in the play-action, you're really trying to suck up the linebacker or the safety. So, it's really on the fake, how the linemen fire out, how they, just the mannerisms and everything. The quarterback has to really sell it, hold it out there and make the guy believe that it's a run play.''
San Francisco safety Eric Reid, who has played against Shanahan's offenses in games and now in practice, said defenders try to key on the helmets of the offensive linemen. If they are high at the snap, that usually means they're preparing to drop back and pass protect. If they are lower, it often means they are trying to get under a defender to get drive on a run block.
The key for successful play-action teams is hiding those intentions, which works especially well when paired with a strong running game like Dallas had last season with Ezekiel Elliott.
''They pair their play action with their runs,'' Cowboys linebacker Sean Lee said. ''They look very similar and they do it really well. That's what makes our team so effective. You're worried about stopping the run because you know you have to stop a guy like Zeke with this offensive line and all of a sudden they get all this play action behind it. It's really, really hard. You have to be disciplined with your keys. You've got to get a good feel for it.''
The use of play action has dropped around the league from about 21 percent of pass plays from 2012-14 to 18.5 percent last season, according to game-charting data from Football Outsiders, as fewer teams relied as heavily on the zone read the past two seasons.
But one play-caller has been a consistent proponent of play action with Shanahan's Atlanta team last year leading the NFL by using play action on 27 percent of pass plays, about 50 percent more than the league average. Since taking his first job as a coordinator in Houston in 2008, Shanahan's offenses have ranked in the top 10 in play action use every season, according to Football Outsiders, also ranking first in 2012 and finishing second in 2014 in Cleveland when Hoyer was also his quarterback.
The strategy remains successful no matter how often it is utilized with teams averaging 7.9 yards per pass play on play action to 6.2 yards per play on other pass plays, according to Football Outsiders, as play action often leads to better protection and deeper throws.
''It's challenging to the back end and us as linebackers,'' San Francisco linebacker NaVorro Bowman said. ''It gives the quarterback holes to see through the defense if you honor the run fake. Or if it is a run, then we're late running downhill.''
AP Pro Football Writers Schuyler Dixon and Arnie Stapleton contributed to this report.
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