Buckle up your chin strap, dear reader. This is not a story for the faint of heart. We’re diving into the NFL pile, a place where rules are abandoned and no body part is safe.

The pursuit of a fumbled ball is, by all accounts, football’s final frontier — the wild, wild mess. While games might be endlessly televised, replayed and legislated, the pile remains the one place on the field shielded from prying eyes.

That might be for the best. It’s not pretty under here.

“Man, it’s no-holds barred,” said Minnesota Vikings defensive end Jared Allen, the Los Gatos native. “Everything happens. I bet that ball changes hands 15 times down there.”

The Pile, as it shall be known, is football’s reverse meritocracy; a place where people are constantly striving to get to the bottom. To get there, players will resort to eye-gouging, arm-twisting and well-placed pokes. It’s a “Three Stooges” routine with shoulder pads.

It also happens to hold the key to the NFL playoffs, which begin this weekend. The top three teams in the league in turnover differential — the 49ers (plus-28), Green Bay Packers (plus-24) and New England Patriots (plus-17) — went a combined 41-7 and earned first-round byes. The 49ers’ mark broke the franchise record of plus-22 set by the 1981 team, the one that launched San Francisco’s dynasty.

To put it simply: Get the ball, get the win. Just ask New York Giants defensive lineman Dave Tollefson, who lived to tell about his game-changing fumble recovery against the St. Louis Rams earlier this season.

“It’s pure pandemonium,” the former standout at Concord’s Ygnacio Valley High told reporters. “You would think that the football had the key to life in it. Seriously. It’s unlike anything I’ve ever been involved in sports.”

As San Diego Chargers linebacker Takeo Spikes, a survivor of 18 career fumble recoveries, said: “If piles could only talk.”

Today, they do.

Here are true tales from football’s sweaty underbelly.

‘He tried to feel me’

The first rule of The Pile is that there are no rules. There is also no code of honor, no professional etiquette, no regard for human decency.

“No, no, no,” Raiders defensive lineman Tommy Kelly said. “There are no other rules other than, ‘Get it!’ However you get it, get it. If you have to bite him, bite him.”

Former 49ers and Raiders linebacker Bill Romanowski was not the kind of guy you’d want to meet at the bottom of a dark pile. He was known as one of the dirtiest players of his day, drawing fines over the years for kicking Larry Centers in the head, spitting in J.J. Stokes’ face and throwing a football at Bryan Cox’s crotch.

So imagine what Romanowski did when shielded from view.

“I used to go to a pretty dark place, and there wasn’t much that was off limits,” Romanowski acknowledged. “I’m not proud of some of the things I did. But I just wanted to win so badly that I would do anything to get a piece of that ball and get it back.”

In the January 1991 NFC Championship game between the 49ers and New York Giants, Romanowski was trying to pry the ball away from running back Dave Meggett. Let’s allow Romanowski, now an analyst for Comcast SportsNet, to give the play-by-play: “I’m trying to rip the ball out of his hands and as I’m ripping, all I could get was a finger. I ripped as hard and as fast as I could and cracked his finger like a chicken bone.”

That brazen, whatever-is-necessary attitude underscores an important fact about life on the bottom: The ball is changing possession, sometimes frequently. That helps explain the ritual dance that plays out on The Pile’s fringes, when players from each team signal with equal certitude that the ball belongs to them.

They might be right, if only for a fleeting moment. As Patriots coach Bill Belichick said: “It’s not who gets the ball. It’s who comes out with it.” New England tied with the 49ers, the New Orleans Saints and the Buffalo Bills this season for fewest fumbles allowed (five).

Getting to the prize is the easiest part.

“You don’t need no skill level to fall on a ball,” the Raiders’ Kelly added. In fact, the true challenge is enduring the outrageous indignities that occur once you have the football. Explained Raiders quarterback Jason Campbell: “They’re pulling. They’re tugging. They’re punching your gut. They’re turning your neck.”

“Guys do what they want to do,” added Houston Texans running back Arian Foster. “I try to be as humane as possible when I play this game. Other people don’t. You can’t account for those.”

Green Bay quarterback Aaron Rodgers accused Seattle defensive end Darryl Tapp of giving him a chomp during the 2008 season.

“It felt like a bee sting,” Rodgers said. “I was looking down and he was biting my arm, so I had to get his teeth off my shoulder.”

When Rodgers went public a season later, Tapp denied it, sort of.

“I’m pretty sure it didn’t happen — pretty positive,” he said.

But Tapp’s tactics have nothing on defensive end Shaun Smith, who was accused not once but twice of grabbing a particularly sensitive region of an opponent last season in scrums. After he claimed his second victim, the 49ers’ Anthony Davis, and received a $10,000 fine, Smith became known in cyberspace as The Genital Giant.

“He tried to feel me,” Davis said. “That’s weird, right?”

Actually, that’s just typical. It’s why longtime NFL linebacker Ben Leber once said: “In the pile you hear some screams of pain, but you don’t know where it is coming from — unless it’s you.”

Sometimes, no one can hear you scream. Barry Sims, the former 49ers and Raiders offensive lineman, recalled the fear of being trapped underneath an avalanche of humanity.

“What went through my mind was: ‘Oh my god, I’m stuck!’ ” Sims said. “It got me thinking of what it would be like to be trapped in rubble, like after an earthquake. I had to calm myself down and remind myself that everyone would be unpiling in a moment. But, boy, it made me realize that being buried alive would be a scary experience.”

Sorting through the pile

While the 300-pound behemoths are playing tug-of-war, the crew of seven officials must keep the peace. Mike Pereira, the league’s former head of officials, said the key is to peel away the players as quickly as possible to locate the ball.

“Once they find it,” Pereira said, “then they worry about who has it. … We recognize that the ball could change hands two or three times before we find the location.”

It makes for an odd scene: the smallest men on the field — many with AARP cards in their wallets — trying to separate a herd of testosterone-fueled brutes. The 49ers’ 323-pound Davis recently tugged daintily on his T-shirt to demonstrate what it feels like when officials are trying to drag him off the scrum.

And when the 49ers and Cincinnati Bengals were fighting over a football earlier this season, 325-pound guard Adam Snyder just plain ignored the officials who were trying to sort through The Pile.

“I’m not getting off until we have the ball!” Snyder recalled yelling.

Pereira, now a Fox analyst, acknowledged the challenge.

“You’ve got a 60-year-old guy who weighs about 175 pounds soaking wet trying to separate those big guys,” he said. “It’s a miracle they don’t get pulled right into the pile with them.”

Officials probably could throw a personal foul flag during every scrum. But that’s not their focus. Their eyes are locked in on finding the ball under what could be a ton of men and equipment. As NFL vice president of football operations Ray Anderson said, “You can’t enforce what you can’t see … I guarantee if we see something, we’d take action.”

An NFL tradition

The importance of pouncing on a loose ball is as old as the game itself. William “Pudge” Heffelfinger, who became the first professional football player on Nov. 12, 1892, celebrated his $500 payday from the Allegheny (Pa.) Athletic Association by recovering a fumble and returning it 35 yards for the game’s only touchdown.

Just like that, the importance of the turnover was born.

Over the years, leather helmets and the wing-T have come and gone, but the value of the old-fashioned scrum has remained the same, as the late Ray Nitschke understood.

The Green Bay Packers Hall-of-Fame linebacker was hailed as the hero of the 1962 championship game after recovering two fumbles against the New York Giants. To hear one former teammate tell it, Nitschke recovered neither. He simply sweet-talked teammates Bill Forester and Dan Currie into sliding him the ball once his Packers had secured possession. “So Ray got credit for two fumble recoveries, became the MVP and won a Corvette — all at the bottom of the pile,” former Packers lineman Jerry Kramer, 75, recalled with a laugh.

Championship history took a sharp detour beneath the stack of human rubble in Super Bowl V. Dallas Cowboys running back Duane Thomas was trying to fight his way across the goal line when Baltimore Colts linebacker Mike Curtis jarred the ball from his hands.

The ball popped safely into the arms of Dallas center Dave Manders. But as Colts players swarmed him, they obstructed the view of official Jack Fette. Colts tackle Billy Ray Smith began signaling wildly in his team’s favor, by yelling, “Our ball! Our ball!”

A flummoxed Fette signaled the same, giving the Colts the ball at the 1. Never mind that Manders got up, still clutching the ball, and pointedly handed it to the referee. The Cowboys on the verge of going up 20-6, instead went on to lose 16-13.

“We ought to give the game ball to Billy Ray,” Colts defensive lineman Bubba Smith later said. “He conned that official right out of the Super Bowl.”

And in the history of the Super Bowl, the team with the edge in turnovers is 33-3 (.916).

‘Get down there and do it’

By all accounts, nobody has it worse than the quarterback. They’re The Pile drivers, the ones most often on the business end of botched snaps, bumbled handoffs and blindside hits that jar loose the ball.

The three players with the most career fumble recoveries all are quarterbacks: Warren Moon (56), Dave Krieg (47) and Boomer Esiason (45).

It’s also why one of 49ers coach Jim Harbaugh’s fondest moments of his 15-year NFL playing career is a play that no one else ever saw. He made a Pro Bowl and led the Indianapolis Colts to within a Hail Mary of making the Super Bowl, but Captain Comeback points instead to the time he was Private Pile.

Looking back on his career, Harbaugh called holding on to a fumble despite searing pain “probably my proudest experience.”

“It was like an arm-wrestling match down there,” added Harbaugh, recalling how he started with half the ball. “I couldn’t lift up my arms after I was done because I was straining so hard down there to get the leverage on the ball.”

As a quarterback, shouldn’t he weigh the danger factor and leave the brutality to the linemen?

“It would be hard to live with yourself if you turned that down,” Harbaugh said. “It would bother a person for all the rest of his life.”

And players never forget what happens in The Pile.

Former cornerback Eric Davis, who spent six of his 13 NFL seasons with the 49ers, remembers the time he discovered Chargers quarterback Ryan Leaf clinging to the pigskin at the bottom of a scrum. Davis grabbed Leaf’s fingers and began bending them backward. Leaf looked at Davis in horror, wondering if he really was willing to break Leaf’s fingers.

Davis just smiled.

“It’s not worth it,” he told him.

Leaf let go of the ball.

Romanowski, upon hearing that story, wondered why Davis took it so easy on the quarterback.

“I would have snapped him,” he said. “Oh, yeah.”

Contact Daniel Brown at dbrown@mercurynews.com and Mark Emmons at memmons@mercurynews.com.