Eight years ago, another one of those seasons when everything was going right for the New England Patriots, Coach Bill Belichick ordered a practice to a surprising and immediate halt.

Randy Moss, the team’s star wide receiver and a major reason the 2007 Patriots would finish the regular season 16-0 before reaching the Super Bowl, was injured – or at least that’s what Belichick told his team. Time to adjust. Who would replace an irreplaceable player, when seconds counted and a potentially historic season lay in the balance? Who would step up, fill Moss’s spot on the field and in the locker room. Who would adopt Moss’s assignments? How could the Patriots machine keep running without someone as vital as Moss?

Moss, in reality, wasn’t hurt. Belichick was running a drill – a crisis simulation designed to test players’ readiness and adaptability – and, according to former Patriots wide receiver Donte’ Stallworth, that’s one of the reasons New England is so rarely blindsided by the NFL’s unavoidable reality of significant injuries, like the one that befell the Patriots on Sunday.

Wide receiver Julian Edelman hobbled off the field after fracturing a bone in his right foot. He’s expected to miss six to eight weeks, though he could return at some point during the postseason. Losing Edelman is a significant blow. He’s the team’s leading wide receiver with seven touchdowns and 692 receiving yards and a major reason the Patriots are 9-0 and are favorites to repeat as Super Bowl champions and claim their fifth Lombardi Trophy since the 2001 season.

This is not a drill, but the Patriots don’t seem to be panicking after losing Edelman. Belichick’s readiness for anything and constant roster manipulation have prepared the team for moments like this. If there is a hallmark of Belichick’s Patriots, beyond 15 consecutive winning seasons and six AFC titles, it is his preparation for the absence of significant contributors and a “next-man-up” culture that has allowed New England to maintain its excellence despite injuries, roster turnover and changing times.

“It’s something that they ingrain in guys: worst-case scenario,” said Stallworth, who spent the 2007 season and the 2012 preseason with the Patriots. “They want you to be prepared for every situation.”

Stallworth, who was on deck to replace Moss if Belichick’s 2007 scenario had become reality, had to know Moss’s assignments as well as he knew his own.

“I already know what’s going to happen. They strategize, and they plan for everything,” said Stallworth, who speculated that although receiver Danny Amendola will fill Edelman’s starting role, other players – including star tight end Rob Gronkowski – likely know Edelman’s assignments and could, if necessary, fill in.

Belichick would stop practices often with similar tests; it wasn’t uncommon, Stallworth recalled, for the coach to surprise players on either side of the ball with questions about situations, no matter how unlikely they seemed.

Every Tuesday, former Patriots running back Kevin Faulk said, the team brought in hopeful free agents – the latest group cycling through to steal someone’s job.

“They’re looking for a diamond in a rough,” said Faulk, who spent his entire 13-year career in New England, including the last dozen seasons under Belichick. “You’ve got to be consistent. You’ve got to understand that. You’ve got to pay attention to the assistants. You can be the guy this week and then the following week you can be inactive.”

Intelligent, versatile players were favored occasionally over more talented ones; one player, no matter his perceived importance, can be replaced because it is the entire machine that must work, not the individual parts.

Even when quarterback Tom Brady, the most essential Patriots player, suffered a season-ending knee injury in the 2008 season opener, New England went on to win 11 games behind Matt Cassel, the backup quarterback who hadn’t started a game since high school.

But a survey of Belichick’s starting lineups also shows certain positions seem more prone to turnover during the continual refreshment of New England’s roster. Offensive and defensive linemen, for instance, seem to be foundation blocks – where value and consistency can be found. Running backs, receivers, linebackers and cornerbacks – where key players are often more expensive and, on occasion, more injury-prone – are more fungible.

Since the 2000 season, when Belichick took over in New England, 10 running backs have been listed as the team’s primary ballcarrier – an indication that Belichick seems to believe any rusher can excel in his system. The evidence supports that: A different back has led the Patriots in rushing in seven of the past 10 seasons; when Dion Lewis, the team’s starting running back, suffered a torn anterior cruciate ligament this month, veteran LeGarrette Blount stepped in for a mostly seamless transition.

Cornerbacks, particularly on the left side of the field, are seen similarly as short-term solutions: In 10 of the past 13 seasons, a different player has started for New England at left cornerback – the most high-profile, and therefore expensive, position in the secondary.

The Patriots, whose hesitance to lock players into long-term mega-deals has made long-term success financially possible, flood their roster with draft picks at those more volatile positions. Belichick has drafted 17 cornerbacks since 2000, more than any other position, followed by 16 linebackers and 13 receivers.

Offensive linemen and defensive ends, though, tend to retain their positions year after year. From 2006 to 2009, the Patriots’ entire starting offensive line remained intact – remarkable stability for the blockers who, at least in Stallworth’s opinion, have allowed New England to be consistent on offense despite constant change at receiver and running back. And, Faulk said, that’s not all.

“Those are skill positions; you’ve got a lot of skill in the world, man,” he said. “I don’t want to say you can replace that any given time, but you can find that. Linemen? It’s not too often you can find good linemen.”

Which is perhaps why Belichick made linemen a priority in drafts, his own kind of doomsday plan: The Patriots have drafted 27 offensive tackles and defensive ends since 2000.

“I guarantee you,” Stallworth said, “there’s no situation that they haven’t practiced, including injuries. Whenever someone goes down, it can always be interchangeable. Anybody can go anywhere.”

Because of that, New England – seemingly no matter what happens – keeps going back to the playoffs. Absent Edelman, Lewis and other key pieces, 2015 seems to be no different, as the undefeated Patriots machine keeps rolling toward its ultimate goal.