THE BOYS HATED the hill. It loomed over every teenage workout like an appointment with an outdoor torture chamber. They could feel it in their lungs and in their legs well before they arrived at the park near their house in Orange, California.

The hill was almost 80 yards long, rows of houses on each side. Its incline increased gradually, until it was almost too much to bear at a full sprint. But every week, the Slater brothers -- Matthew and David -- would slog their way to the top, again and again. Their father, Hall of Famer Jackie, would stand, stoic and stern, at the base, a stopwatch in his hand. He'd give the two boys 18 seconds to reach the summit of the hill. If they didn't make it, the rep did not count. When they came back down, legs wobbling like newborn colts, they had 45 seconds to rest. Then it was time to sprint again.

"Running up that hill was no joke," Jackie says now. "If you go up it 10 times, it takes everything out of you."

This was a test of faith, and of commitment. The father did not want his sons playing football. He had endured thousands of collisions during his 19-year NFL career; he'd torn ligaments and mangled joints blocking giants of the game like Reggie White and Joe Greene, and he didn't want that for his boys. He tried to steer them toward other sports, like track, but they kept begging to play football, Matthew in particular. Keeping them away from pads only intensified the longing. "Matthew had asthma, so I always wondered if he'd have the cardiovascular strength to even play," Jackie says. "But he said he wanted to be a pro football player, and I had to find out if he could hold up to the rigors of the game."

As a deeply religious man, the father felt a test of faith brought out the best in people. Here was the chance for his boys to prove that they were up for this. Slater had played with Walter Payton in college, and each offseason Payton famously molded his body into iron by sprinting up the dusty hills near his Mississippi home.

Most of the hills in California were concrete, but this one was grass. Jackie had run it often during his career with the Rams, his boys watching quietly at the base of the hill. When the time came, he decided to reverse their roles.

"He didn't say a lot, but I remember him looking at us like: 'Hey, you wanted this, didn't you?'" Matthew says.

If you want to understand the origin story of the most unlikely NFL career of this era, that California hill is probably the best place to begin. Matthew Slater willed himself to climb the steep grass-covered incline hundreds of times. It became a metaphor for his entire career. He might have been born into NFL royalty, but that meant nothing standing at the bottom of the hill.

Since his rookie season in 2008, Slater has an NFL-best 131 special-teams stops. No one else has more than 104. John Huet for ESPN

THERE SEEMS NO logical reason that Slater should be entering his 12th year with the Patriots, or that the least sentimental franchise in professional sports considers Slater -- an undersized wide receiver who has caught just one pass in his NFL career -- such an important part of its team culture that it has kept him around longer than anyone besides its kicker, Stephen Gostkowski, and a quarterback named Tom Brady, a guy you might be familiar with.

Each year, Patriots come and go, many traded away or outright released the minute Bill Belichick believes their salaries (or attitudes) are outweighing their impact. But Slater, improbably, has remained.

There is a real case to be made that Slater is as good at his job -- playing special teams -- as anyone in football. He's been voted to the Pro Bowl seven times, the same number as Aaron Rodgers, Von Miller and Antonio Brown. (It's also the same number, coincidentally, as his father.) For a decade, he's been a headache for opposing special-teams coaches, consistently beating double-teams and blowing up punt returns. But just as important, he might be the best marriage of selflessness and specialization of this NFL era.

Case in point: Do Slater's skills have as much impact as, say, Rodgers' ability to throw a football or Khalil Mack's devastating pass-rushing talents? It's hard to make a leap that generous. Slater, in fact, belly-laughs at the suggestion during an interview at his home the week before Patriots training camp. But if you study the film of the Patriots' 13-3 Super Bowl win last season, you can argue he was as important as anyone (including Brady and MVP Julian Edelman) to New England's win.

The Patriots punted five times against the Rams. Slater downed a punt on the 2-yard line, knocked another out of bounds at the 6, and tackled returner JoJo Natson for a loss on a third. The Rams' offense, which came into the game as the NFL's most prolific unit, could not escape the shadow of its own end zone, and the Patriots' special teams were a big reason for that.

"I know it wasn't everyone's favorite Super Bowl, but it was definitely mine," Slater says. "It was just so rewarding to see all the years of work that we'd put in coming to fruition. ... To put our defense in a position where they could play one of the best Super Bowls in history was so rewarding."

The reality of Slater's existence, however, is that he is beginning to look like the last of his kind. With each passing year, special-teams play seems to engender greater scrutiny. For several seasons, there have been discussions -- driven by the league's desire to reduce the number of vicious, dangerous collisions -- about eliminating kickoffs. Troy Vincent, the NFL's executive vice president of football operations, admitted in an interview with Dan Patrick last year that the idea of eliminating punt returns has come up for discussion. As the NFL tries to figure out how to balance its violent traditions with the reality of the game's uncertain future, it's easy to imagine that a career like Slater's won't be feasible a decade from now.

Whether that's a worthwhile trade-off is a different debate, but the truth is evident: Slater is carrying a torch that represents a certain kind of invaluable role player (Hank Bauer, Bill Bates, Albert Lewis, Steve Tasker, Larry Izzo, Brendon Ayanbadejo) who has been a part of the league since its inception. And the torch appears to be flickering.

"If you start messing with special teams, I think you start messing with the fabric of football, and that's a little sad in a way," Slater says. "I understand the desire to make the game safer, and if you take away an area that has some of the biggest collisions, you feel like you'll be taking some of the violence out of it. But the goal line iso is a pretty violent play, right? Do we get rid of that too? I don't think anyone would argue for that. Obviously, I'm biased, and I'm not blind to that. I just think it's important to understand that for a long time, the kicking game was the whole game."

One name in particular comes to mind for Slater when he thinks about the impact of special teams: Tasker, who made seven Pro Bowl appearances with the Bills and who is arguably the greatest gunner ever on punt coverage. "To me, you can't tell the history of the 100 years of the NFL without saying the name Steve Tasker," Slater says. "If he hadn't done his role at such a high level, I'm not sure guys like me would have a job."

Tasker, who has worked in TV and radio since he retired in 1997, shares Slater's concerns about how eliminating special teams would alter the sport's DNA. "Teams have been de-emphasizing it," Tasker says. "But the simple fact of the matter is, it's changed a lot over the years with the rule changes. The wedge isn't there; you can't hit the long snapper. If you're a kickoff cover guy, you might only have to cover one kick a game. There is only so much a great special-teams player can do for you. What are you getting out of him if you're hanging on to him for 10 years? You have to ask that question."

Which makes Slater's longevity, particularly in this era, especially with one team, even more remarkable in Tasker's eyes. He also can't help but feel a bit of a kinship with Slater that links one generation to the next. Ask them both what qualities they think make a great special-teams player and they come up with eerily similar answers: selflessness, toughness, fearlessness, adaptability and a willingness to be physical. Tasker (at 5-9, 185) and Slater (at 6-0, 205) might have had physical limitations as receivers, but both possess an intuitive ability to juke defenders at the line and then track a ball they can't see, based primarily on the ability to read the eyes of the man trying to catch it-all while running at top speed in a sea of chaos.

"I have so much respect for Matthew. ... I hope he dwarfs whatever I ever did," Tasker says. "Somebody asked me about him early in his career, and I said it was obvious he knew what he was doing when he was covering kicks. He has a real gift for it."

Tom Brady and the Patriots say Slater is crucial to their dynasty. Greg M. Cooper-USA TODAY Sports

GETTING BILL BELICHICK to gush about any of his players, including Brady, often feels like you're engaging in a contentious deposition. But over the past 10 years, Slater has been the rare exception. In 2013, when he was voted to his second straight Pro Bowl, Belichick let fly what is arguably the most effusive string of compliments of his entire coaching career.

"Matt's really ... he's tremendous," Belichick said. "His attitude, his work ethic, the example that he sets, the way he interacts with his teammates in a really good way. I don't know that a player could do any more than what he's done for us in that role for the last several years. He's embraced his role on the team, he's been very good at it and he makes other players around him better. I think that's a great compliment to him and the job he does. He's smart, he's well prepared, he works hard, he has good skill, good talent, he's tough, he's a good playmaker for us. I could go on about him all day."

When Slater's contract was up last year, he took a free agent visit to the Steelers -- only to re-sign with the Patriots a few days later when they offered him a 75 percent raise over what they had paid him the previous season. The Patriots told Slater's agent that he was as important as anyone to their locker room culture -- Brady included -- and that they wanted him back.

This came after he missed seven games in 2017 with injuries, months before his 33rd birthday -- and in the era of the latest CBA, in which GMs looking to save a penny almost always choose cost-controlled young players over seasoned vets.

Such is the degree to which the most revered franchise in football reveres Slater -- yet the most fascinating aspect of his career is how close it came to never happening in the first place.

Sure, he had the pedigree and natural football instincts, plus a thirst for contact. "Our very first parent-teacher conference, in kindergarten, was about trying to get him to stop tackling any little boy or girl with a ball," Jackie Slater says. "I know it was serious, but I couldn't help but feel a little proud."

But much of his childhood was spent anticipating the growth spurt that would enable him to match his dad's 6-foot-4, 227-pound frame -- a growth spurt that never came. Every annual trip to the pediatrician was a source of frustration.

He was 5-6 and 150 pounds when he got to high school, so the only logical position for him was wide receiver. But he didn't catch a lot of passes even after, eventually, he grew 6 inches. His team ran the ball almost exclusively, so he did a lot of blocking. Opposing players who knew who his father was would often come looking for him, eager to prove something about themselves. He didn't mind. "I was definitely aware of it," he says. "But I learned to love the competition."

A dedicated student, he got into Brown and Dartmouth and took trips to both. But when Slater, who was also a track standout, finished second in the state in the 100-meter dash as a senior, UCLA suddenly took an interest. It was impossible to resist the draw of big-time football.

Then, over the course of four years, half his career with the Bruins seemed to get swallowed up by injuries. The coaches moved him from wide receiver to corner, but he rarely played.

It wasn't until his senior year that he asked if he could return kicks. Overnight, he became one of the best in the country, ranking first in the Pac-10 in kickoff return average and setting a UCLA record with 986 yards in 13 games.

But he still wasn't optimistic about his football future. "I was really starting to think about going into the ministry," says Slater, whose faith has been an important aspect of his life since childhood. "I was looking at the next step in my life beyond football."

Then one day during his final season at UCLA, a scout from the Patriots pulled Slater aside after practice. "The conversation lasted maybe 10 or 15 seconds," Slater says. He doesn't even remember who the scout was. But it changed everything. "He told me the Patriots had been watching film on me and that I had a future in the NFL doing something. That gave me just enough motivation to finish the year strong."

He didn't get invited to the NFL combine and went on only seven predraft visits with teams. The Patriots, who eventually picked him in the fifth round, weren't one of them. "When they drafted me, it kind of felt like it came out of nowhere," Slater says.

The first several months were a blur. He felt like an impostor. Physically he could compete, but intellectually he was lost. The Patriots-unsure what position he might play-had him working with the wide receivers and safeties, and in the kicking game. Every day, he thought someone would tell him it was over. "We called the guys who would tap you on the shoulder the Grim Reapers," Slater says. "You'd sit at your locker every day after practice and just wait for an intern to find you and say, 'Hey, Coach wants to see you. Can you bring your playbook?'"

He earned a spot returning kicks, but for most of his rookie season, every week felt like it might be his last. He went back to imagining his future in ministry -- daydreaming about using his time with the Patriots as part of a future sermon, watching people's eyes grow wide when he brought up what he learned from the few months he spent in the NFL. He and his father spoke often about the Bible verse Romans 8:28 -- the idea that whatever his fate was, the journey was more important. And we know that in all things God works for the good of those who love him, who have been called according to his purpose.

His anxiety came to a head in a late-November game against the Steelers when he muffed a kickoff in sloppy conditions, the ball bouncing comically off his face mask inside the 10-yard line, igniting a blowout loss. "It was the lowest point of my career," Slater says. "I felt like I'd cost us the game, and that was just the cherry on top of a rookie year where I felt totally lost. I figured I was done, and so did the other rookies. I know a lot of New England fans wanted me out of here, and a lot of them probably still remember me for that play."

The reaper never appeared. Slater refocused on the coverage game that saw him record 25 tackles as a senior at UCLA -- he had 12 for the Pats in that rookie season -- and served as the gunner on punt coverage. For Belichick, whose coaching career began with special teams, grooming a promising special teamer into a no-nonsense blocking threat came easily: Linebacker Larry Izzo served the same role for Belichick for eight seasons as special-teams captain in the early 2000s (making three Pro Bowls himself). "To play for [Belichick] has been incredible, but that isn't to say it's been easy," Slater says. "It's been hard. His standard is high, and there is no gray area. It's all black-and-white, but I think you learn to appreciate that. No coach or player is bigger than the team."

In time, Slater blossomed in his new role. In his third season in New England, he led the team in special-teams tackles with 21. And by 2011, he was the unit's captain (a designation he's held ever since). He again led the team in special-teams tackles but added kickoff returns back to his résumé. That winter, Slater was voted to his first Pro Bowl.

These days, Slater also serves as an unofficial team therapist in the New England locker room -- including on those days when the Patriots' ruthless approach to roster turnover dispatches a popular veteran, sending shock waves through the teammates left behind.

"He keeps the locker room together," Patriots running back James White says. "He makes sure it's a family-like atmosphere in this building. There can be some tough days, there can be some easy days, but he's the guy that kind of keeps everybody locked in and keeps that great camaraderie throughout this team."

One season, Patriots linebacker Gary Guyton pulled Slater aside and asked if he'd be up for a blind date with a friend of a friend, a doctor working in Rhode Island. Guyton thought they'd be into each other. Slater was skeptical, and so was the doctor, Shahrzad Ehdaivand. Now, nine years later, they're married and have a son, Jeramiah, and a daughter, Hannah. As Slater sits in his living room before this year's camp opens, they are expecting their third child any day now.

It's hard for him to put into words how different, how much less fulfilling, his life might be if football and faith hadn't been working in tandem to steer him to where he is now.

"Again, it comes back to Romans 8:28," Slater says. "Sometimes there is going to be pain, and sometimes it's going to be tough. But there is a purpose to it all."

"He keeps the locker room together," James White says. "He makes sure it's a family-like atmosphere in this building." John Huet for ESPN

EVERY OFFSEASON, MATTHEW Slater tries to get back home to California, and when he's there, he tries to sprint to the top of that hill. It's as hard at 33 as it was at 13. No one outruns the football reaper forever. But the hill is the best way to try.

He doesn't know how much longer he wants to play, but he knows the day will come, eventually, when he does get a tap on the shoulder. It's going to hurt a little, even if he understands the logic behind it. The league is changing. The way teams put together their rosters is changing. Metrics don't measure locker room leadership. Even at 33, he's still one of the fastest Patriots. But for how long?

"I'm not going to lie, it will sting a bit," Slater says. "I'm human."

But when that day does arrive, he plans to devote himself fully to supporting his wife, who put her medical career on pause to stay at home with their kids while he chases punt returners. The next step, he believes, will also feel like part of God's plan.

Someday he'd like his son to run the hill with him, whether he has a future in football or not. "That hill has a lot of meaning to my family," Slater says.

It's a rite of passage, a baton passed from one generation of Slater to the next. Every trip to the top has to be earned, then earned all over again.