Might be hard to believe while watching Aaron Rodgers, Russell Wilson or Ben Roethlisberger in the playoffs this weekend, but it wasn't all that long ago that the shotgun formation was something of a curiosity in the NFL, used less than once every five plays in 2006.
In today's pass-heavy era populated by players who became accustomed to spread offenses in high school and college, most teams use it most of the time: This season, 60 percent of offensive snaps began with the quarterback 5 yards or so behind the line of scrimmage.
During their first 10 plays in the wild-card round, the four winners - Rodgers' Packers, Wilson's Seahawks, Roethlisberger's Steelers and Brock Osweiler's Texans - used the shotgun a combined 67.5 percent.
Still, the case could be made that the shotgun - a novelty when Tom Landry's Dallas Cowboys went to it primarily for third downs and 2-minute drills in the 1970s, then popularized more recently after Bill Belichick's New England Patriots had success with it in the 2000s - has reached a tipping point, and it's time for teams to be more judicious about the formation.
For the season, 78.9 percent of passing plays and 32.5 percent of run plays started in shotgun, according to data provided to the AP by TruMedia Networks, whose chairman is Tony Khan, the son of the Jacksonville Jaguars' owner.
''Some teams, it seems like they're in shotgun all the time,'' Hall of Fame quarterback Warren Moon said. ''And it won't go away. Until somebody figures out how to slow it down, you'll keep seeing a lot more shotgun going on.''
That might very well be.
After all, as Moon and others point out, a big explanation for the rise of the shotgun is that quarterbacks arrive in the pros having spent their formative years operating that way. By taking a shotgun snap, instead of being handed the ball directly by the center, a QB has an easier time reading an opponent's defensive alignment. He also gets more time to find someone to throw to before a rusher is in his face.
''It's here to stay. It's in the program. It manifests,'' former NFL player and head coach Herm Edwards said.
Edwards said that when he's told players at a high school all-star game to line up right behind the center, ''They look at me like, `Hey, Coach. We don't do that.'''
Notably, most of the league's very best offenses relied comparatively little on the shotgun this season. The five highest-gaining teams (Saints, Falcons, Redskins, Patriots, Cowboys) all ranked among the eight that used the shotgun least frequently.
Four of the five teams that used the shotgun most ranked among the 10 poorest-performing offenses. One example: The San Francisco 49ers were in the shotgun 77.6 percent of the time (add in the pistol, with a smaller gap between center and QB, plus a running back hidden in the backfield, and the figure tops 90 percent) and were 31st of 32 clubs in average yards.
Chip Kelly, who was fired after one year as the Niners' head coach, likes the pistol because ''your quarterback now can be a factor in the run game.''
At the other end of the spectrum: Under offensive coordinator Kyle Shanahan, Atlanta accumulated 415.8 yards per game, No. 2 in the NFL, while being in shotgun a league-low 37.5 percent of plays.
''Every time you're under center, you've got a lot more run options and a lot more play-action options and a lot more movement options off of your runs,'' Shanahan said. ''Your play choices are endless. You can do everything. Once you get into the `gun, certain things are like cut in half. Play-action is not as good because it happens quicker. You can't hold the ball out there for as long and stuff. It just eliminates being as balanced.''
One of his mentors, recently retired Denver coach Gary Kubiak, ran the second-fewest shotgun plays this season (41.6 percent). And while Kubiak also said he likes the way the shotgun helps the run, he noted there's no set-in-stone formula for success.
''It all depends what you are, how you're built,'' Kubiak said. ''How your quarterback plays back there.''
According to the 2016 data, though, teams actually put up better running numbers in the shotgun (4.95 yards per carry) than out of it (3.82). And passing was more efficient out of snaps under center, with a 63.6 completion percentage and 7.99 yards per pass attempt vs. 62.8 percent and 6.93 yards from the shotgun.
The key, it turns out, might be moderation: With Tom Brady running the show for Belichick, the Patriots never started less than 43.4 percent, or more than 55.6 percent, of their plays from the shotgun in any season from 2011-15, reaching at least the AFC title game every time.
''In the NFL, and football in general, it's whatever the hot flavor of the month is, and it goes through the trends,'' Moon said. ''This is a trend that became pretty popular.''
AP Sports Writers Josh Dubow, Charles Odum and Arnie Stapleton contributed to this report.
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