FOXBOROUGH -- In early 2000, Bill Belichick made three hires to round out his first staff with the Patriots, filling entry-level coaching assistant jobs that offered little creative freedom, even less financial freedom, and virtually zero life freedom.

"The 20/20 deal," said Patriots tight ends coach Brian Daboll. "Twenty hours a day for 20 grand a year. And it wasn't exactly 20 yet."

Recommended by Nick Saban, his boss at Michigan State, Daboll interviewed at the old Foxboro Stadium for several hours. He spent the morning in solitude, accompanied only by a pen, notepad, and the damn grainy game film that required him to squint or rewind to identify players' numbers.

Mark Jackson's tryout lasted several days. The staff's second coaching assistant and a holdover from the Pete Carroll era, Jackson was given a handful of NFL games to analyze in painstaking detail. Days later, he presented the project to Belichick.

"I thought an interview was an interview," Jackson said. "You come in, tell him (about yourself). This was more of an assignment."

And Ned Burke, the third coaching assistant, was brought over from the Jets. He didn't officially interview with the Pats. No need after what he went through to get hired by New York.

Burke had originally connected with Belichick in the late 90s at the Belmont Stakes, of all places. Eric Mangini was the link; Burke's childhood best friend went to college with Mangini, who was at the horserace with Belichick. The two groups convened, and Belichick sat next to Burke. Belichick soon learned that Burke had been a two-sport athlete at Cornell: a running back on the football team, and a four-year starter at midfield for lacrosse. The latter was of the utmost interest to Belichick.

"He just started grilling me about lacrosse," Burke said, "and what I thought about the game and where it was going. We talked for quite a while about lacrosse, not even about football."

They left Belmont Park with an agreement: If Burke ever wanted to venture into coaching, he should contact Belichick.

He did, and, as a trial, the Jets began to mail game film for Burke to analyze. Working as a teacher at a small private high school in Connecticut, Burke completed the breakdowns in his spare time and mailed them back. This correspondence lasted four or five months until the Jets finally gave him a shot in the scouting department.

When Belichick went to New England, Burke followed for a coaching assistant gig that is as enticing as it is unenviable.

That first year, Jackson picked up Daboll at 4:30 a.m. They often arrived to yellow sticky notes on their tiny desks -- either assignments from the head coach or corrections on previous assignments. Early in Josh McDaniels' three-year run as a coaching assistant, he'd submit a project and receive "like 100 sticky notes" from Belichick.

Even Belichick will concede that the job is "a grind."

Why wouldn't the interview be, too?

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So you want to get your career started under Bill Belichick...

Cool. You will be a coaching assistant. Know this: Few people will be aware of your professional existence. All public credit for the gameplan -- for which you help lay the foundation -- will go to Belichick and the coordinators. You will occupy a four-sentence bio deep in the team's media guide, and that's about it.

Few people outside the building will be aware of your actual existence, too. Filling out a timecard, especially under Belichick, is akin to keeping a log of when you are awake. The pay, at least initially, is laughably low, and the work itself is an endless brain-frying loop.

"Incredibly laborious," said Burke, who has since embarked on a finance career, "but very educational."

The job is also a well-established launching pad, providing an invaluable base of knowledge for young coaches. It was a starting point, almost a rite of passage, for Daboll, McDaniels, Matt Patricia, Nick Caserio, Bill O'Brien, George Godsey, Josh Boyer, Brian Flores, and Steve Belichick, among others.

Its essence: Entry-level coaching assistants are responsible for weekly breakdowns of the upcoming opponent, handed in to Belichick more than a week in advance of the game so he can use them as reference points as he conceives a strategy. Offensive assistants focus on the opponent's defense. Defensive assistants focus on the offense. Both focus on details so insignificant that you'd think Belichick was playing a prank on these kids.

New England Patriots quarterbacks coach Josh McDaniels, right, confers with head coach Bill Belichick on Tuesday, Aug. 23, 2005.

Phil Savage, who worked as a coaching assistant in Cleveland under Belichick, remembers logging the direction in which the quarterback turned his head prior to each snap.

For many years, these breakdowns were recorded on what Belichick called "the pads." Coaching assistants would diagram each play, illustrating receiver splits, depth of routes, depth of the halfback behind the quarterback, alignment of the defensive players, shades of the defensive linemen, the protection of offensive line. Notations for each category were made at the top of the page.

"There was a box and a location to put it down, and then you had to draw each play by hand," said McDaniels, a coaching assistant from 2001-03. "And I'm not talking about a rough drawing. I'm talking about a drawing that would take you 10 minutes."

Between the identification of scheme and detail, each play could take as long 20 minutes to diagram in full. Each game had 50-70 plays on each side of the ball. Each coaching assistant had three breakdowns per week. Game breakdowns, not mental breakdowns. Although one could lead to the other.

As technology has advanced, "the pads" have been replaced, but fundamental demands of the position, the radical levels of detail, have not changed.

In this job, McDaniels said, "you learned the most valuable lesson that you keep to this day: everything is important."

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Belichick has always sought to hire high-IQ, high-potential individuals, the kind of people who love the grunt work, but eventually outgrow it. "PhD-type people," Belichick used to say in Cleveland, according to former Browns coaching assistant Kevin Spencer. He also has sought toughness, and his interview techniques aim to assess just that.

"Those interviews are long days," Belichick said. "I think you see after 8, 9, 10 hours of an interview you see what kind of staying power they have, how excited they are to keep grinding through the information, how detailed they are, how important it is to them."

The morning begins in isolation. The candidate arrives and is sequestered to work on an extensive film breakdown. This can be a stress-inducing start, considering the absurd level of detail required.

Daboll, for example, was given several hours. When his time expired, he looked down and thought, wait a minute, this can't be right. He had finished about eight plays.

"Come to find out that those pads take like 8-10 hours to do, for one game," Daboll said. "Unbelievable."

When he interviewed in 2001, McDaniels did "five plays in an hour, maybe."

Then comes the intimidating part. The prospective coaching assistant, undoubtedly concerned about the minimal number of plays he just spent several hours diagramming, meets with several of his potential bosses.

"It puts them on the spot," Belichick said. "You're talking to a half-dozen people. What kind of poise and presence does he have in a group?"

Together, assistant coaches pepper the candidate with all sorts of questions -- football scheme and philosophy, application of such philosophy, career aspirations, etc.

"They're pushing you and testing you and seeing if you're going to break a little bit," McDaniels said. "...It was basically a test of whether or not I was willing to work the way they knew I was going to have to work, even though I probably didn't know it at the time."

Added Patricia, who left a lucrative job as an applications engineer to pursue coaching: "This was much more intense than a lot of those engineering interviews I went on."

New England Patriots tight end coach Brian Daboll (AP Photo/Steven Senne)

Interviewing at the old Foxboro Stadium, Daboll was brought into a makeshift staff room, tables pushed together to seat all of the coaches: Charlie Weis, Dante Scarnecchia, Ivan Fears, Seth Davidson, Dick Rehbein and Brad Seely.

Daboll was well prepared. He had spent two years as a grad assistant at Michigan State under Saban, so could speak semi-comfortably about scheme, self-scout, all that. Then Scarnecchia asked him about salary.

What do you think you should make?

Daboll had researched this, too. He had made calls to colleagues, and had dug up salary surveys from the NFL Coaches Association. He believed the average annual salary was around $65,000. He also thought, having worked for Saban, that he was a tad better than average.

"So I say 70," Daboll recalled. "And Brad Seely leans over and says, 'Would you take 15?' I go, 'Yessir.'"

Daboll left the room feeling somewhat embarrassed. "Oh my god," he thought, "I can't believe I just said that." Next up: His one-on-one with Bill Belichick.

And that went well. Daboll remembered "a great conversation -- very, very thorough." McDaniels absorbed the magnitude of the moment -- "here I am, a 23-year-old kid in his office," he said -- but always felt, even dating back to that day, that Belichick was an easy person to talk to. For Patricia, the back and forth with Belichick was "awesome." Belichick was constantly examining how Patricia's mind worked, how he solved problems.

"We sat down and, God, it seemed like forever," Patricia said, "but it was almost like a chess match."

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Bill Belichick hired Matt Patricia to be a coaching assistant in 2004. Picked him over a handful of other candidates that interviewed.

As reported by Tim Rohan of The MMQB, there was initial hesitation on Patricia's part. Had to consult his wife. The Patriots didn't like hesitation. They pulled the offer, according to Rohan, and only put it back on the table after a friend of Patricia's, former Patriots director of operations Nick Carparelli, convinced Belichick that Patricia badly wanted the job.

Daboll has a similar story. The Pats officially offered the position to Daboll on a Sunday, a few days after he had interviewed.

"Of course I want the job," Daboll said.

The response on the other end of the line: "OK, we've got a flight for you today."

This is how the Patriots operate, even with entry-level positions. No time wasted. These jobs seem unimportant, and the work seems trivial (which way did the quarterback turn his head?), but this is how Belichick creates a foundation for young coaches. After all, it's how Belichick himself got started with Baltimore in 1975.

"It was a low-paying job for me, but it was probably the best job I ever had because I learned so much," Belichick said. "And I felt like, other people who would want to do that, not for the money but do it because they really wanted to learn the game and enjoy that kind of a grind to be honest with you -- because it is a grind, but it's beneficial in the long run -- that was kind of the person I was looking for."

The benefits of an otherwise undistinguished job are obvious in New England, where coaching assistants earn promotions faster and more regularly than they do with other NFL franchises.

There are a few logical explanations: Since Belichick was hired in 2000, 21 teams, or 66 percent of the league, have cycled through at least four head coaches. Insane turnover exists throughout the NFL, preventing steady opportunity for advancement within many organizations.

But even in comparison to other well-tenured NFL head coaches, Belichick promotes coaching assistants at a higher rate. Under Belichick, 15 of the 19 coaching assistants listed in the team's media guides received promotions. Due to departures and internal reassignment (i.e. moving a wide receivers to running backs coach), the Pats have filled 24 position coach jobs during Belichick's tenure. More than half the time -- on 15 occasions -- they have hired a former Patriots coaching assistant.

Belichick has filled offensive and defensive coordinator jobs seven times, and four of those hires started their NFL careers as Patriots coaching assistants (McDaniels, hired twice as offensive coordinator, O'Brien and Patricia).

New England Patriots coach Bill Belichick reacts on the sidelines in the first quarter against the Dallas Cowboys in Foxboro, Mass., Sunday, Nov. 16, 2003. (AP Photo/Elise Amendola)

Consider Green Bay under Mike McCarthy. To fill position coach vacancies, the Packers have made seven outside hires and promoted coaching assistants four times. None of McCarthy's quality control coaches have ascended to coordinator jobs in Green Bay, although Ben McAdoo, a quality control coach under McCarthy in San Francisco, has gone on to become the head coach of the Giants.

Cincinnati's Marvin Lewis, the NFL's second-longest tenured coach behind Belichick, has made 12 true outside hires, twice re-hired former assistants (Hue Jackson in 2013, Kevin Coyle in 2016), three times promoted a position coach to a coordinator role, and three times promoted an entry-level quality control coach to position coach.

In Philadelphia, Andy Reid employed a Belichick-like philosophy, promoting eight quality control coaches during his 14 seasons. This is rare, as opportunity for advancement in New England trumps opportunity for advancement almost anywhere else.

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The key, of course, is connecting with Belichick.

Sometimes it's by happenstance. Hell, Belichick met Ned Burke at the racetrack. One of Belichick's first quality control hires with Cleveland in the 90s, Kevin Spencer, played college lacrosse at Springfield, facing off against Belichick's Wesleyan teams. They became friends in the late 70s, when Belichick was working for the Lions and Spencer was teaching and coaching at Detroit County Day High School. Belichick hired Spencer in December of his first year to alleviate the onerous workload of Savage, who was deeply regretting the $5,000 bonus he accepted for doing the pads on both sides of the ball.

Mostly, though, Belichick has relied on referrals. He knows his coaching assistants are eager, maybe desperate, for a promotion and a pay raise. So he implores them to find capable replacements, as was the case when Daboll recruited McDaniels, also a Michigan State graduate assistant.

"Look," Belichick told Daboll, "if this doesn't work out, you're going to be doing this, so you better make sure that Josh can do what he needs to do."

Daboll became wide receivers coach in 2002. When McDaniels earned the bump to quarterbacks coach in 2004, word came down from Belichick that the Pats needed another coaching assistant. So McDaniels and Daboll combed through resumes. They found Matt Patricia's. Seemed smart enough.

"If you need to recommend somebody," McDaniels said, "you need to be damn sure that the guy is going to hold up his end of the bargain."

Best-case scenario for any candidate: After a grueling interview, Belichick calls to hire you. That's a thrill, a life-altering moment. And then someday, after years of charting depths of routes and linemen shades and God knows what, Belichick calls for your help in hiring someone else. That's got to feel pretty good, too.