Grant Cohn: 49ers' retooled play-action game a winning bet

The best bet in Las Vegas right now is the 49ers. To understand this, you have to understand what play action is and why it's so gorgeous. It's the key to the Niners' 2017 season.

Bill Walsh described play action as 'the single best tool available to take advantage of a disciplined defense.' Here's how the play works.

The quarterback receives the snap from the center, turns to face the running back in the backfield and takes three steps toward him. Then, the quarterback reaches out with one arm and holds the ball directly in front of the running back as if to hand it off to him.

But the quarterback doesn't it hand it off. Play action is a fake run. The quarterback keeps the ball, yanks it back and hides it behind his hip so the defense can't see it. 'As the ball is pulled back,' Walsh once wrote, 'the arm normally used to make the exchange is allowed to swing away from the faking back just as it does when the hand off is made.' Picture Joe Montana waving one arm toward the defense with his hand open to show it's empty.

As the quarterback waves his arm, he also stares at the running back for a split second as if the back has the ball. This sells the fake and creates what coaches call, 'a conflicted defender.'

This defender, usually a linebacker, thinks he needs to chase and tackle the running back. As the linebacker pursues, he takes himself out of position to defend the pass. The quarterback throws the ball to a receiver running through the area the conflicted defender should have been covering. Quite a conflict for the poor linebacker.

This is the beauty of play action.

Think of it as a changeup in baseball. It looks like a fastball, it's thrown like a fastball, but it's not a fastball. And when a pitcher throws it well, the batter swings too early and whiffs.

But, sometimes the pitcher tips the changeup. Telegraphs it to the batter. Lets him know it's coming. And the batter smashes the changeup out of the park. The same principle applies to play action.

Last season, the 49ers tipped their play-action passes, which is why they ranked 22nd out of 32 teams in play-action efficiency (yards per play).

How did the Niners tip these passes? Who was at fault? Was it the quarterback? No. Was it the running back? No.

It was the offensive linemen.

Before I explain how they tipped the plays, you need to know there are two types of play-actions passes and the difference between them. Stay with me because we're getting deep into football now.

One type is called an 'action pass.' This involves the offensive linemen selling the 'action' of a run by blocking as they would during a run play, meaning they move forward while the quarterback fakes the handoff.

The other type is called a 'play pass.' This involves the offensive linemen blocking as they would during a pass play, meaning they retreat while the quarterback fakes the handoff.

The 49ers primarily used play passes last season. Play passes are much less effective than action passes because they completely defeat the purpose of the fake handoff. They create no conflicted defenders — the O-line tips them off. The linebackers immediately recognize pass protection and know not to chase the running back.

For whatever reason, Chip Kelly favored play passes last season in play-action plays. He's a very bad coach and now he's unemployed.

The 49ers' new head coach, Kyle Shanahan, favors action passes. This is why his offenses rank near the top of the league in play-action efficiency every season. This is why the 49ers hired him.

Last season, his Falcons offense ranked second in play-action efficiency with 10.4 yards per play. In 2015, his offense ranked sixth in play-action efficiency with 8.8 yards per play. And in 2014, when Shanahan was with the Browns, his offense also ranked sixth in play-action efficiency with 8.8 yards per play.

I want to focus on the 2014 season with the Browns, because that offense didn't have much talent and its starting quarterback for 13 games, Brian Hoyer, will be the 49ers starter next season.

Hoyer isn't a great quarterback — his career passer rating is 84.8. But he is a very a good play-action passer. His quarterback rating on those plays with Shanahan in 2014 was 99.2 according to Pro Football Focus.

That's why the Niners signed Hoyer. He's a perfect fit in Shanahan's action passing game. Together, Hoyer and Shanahan will significantly improve the 49ers next season. I think the Niners will win nine games.

And that brings me back to my initial point about the best bet in Las Vegas. Oddsmakers have set the over-under for the 49ers' win total at 4.5. That means if you bet the 'over,' and the Niners defeat only five teams next season, you win money.

Bet the 'over.'

Grant Cohn writes sports columns and the 'Inside the 49ers' blog for The Press Democrat's website. You can reach him at grantcohn@gmail.com.