The NFL is a copycat league, or so the cliche goes, and 31 teams are constantly trying to copy whatever strategy helped the 32nd team win the Lombardi Trophy. That’s certainly the case with the New England Patriots, winners of three of the past four Super Bowls.

A number of NFL trends can be tied, at least in part, to a desire to do things the Patriot way: defensive coordinators flirting with the 3-4 alignment, front offices cutting costs on the offensive line (except at left tackle), and coaches using defensive players on offense to create size mismatches. But one of the most important aspects of the Patriot dynasty is also the most difficult to copy: New England’s outstanding depth.

Most NFL teams will begin the 2005 season believing they can contend for the Super Bowl if they can just avoid injuries. But that’s just not good enough in the NFL. A well-built team must be able to excel even after suffering numerous injuries. No team has demonstrated this over the past two years more than the Patriots.

In 2003, New England started more than 40 different players, the most of any Super Bowl team in history. In 2004, they started 39 different players. Both starting cornerbacks were lost for most of the season; no. 1 receiver Deion Branch missed half the year, as did starting right tackle Tom Ashworth; Pro Bowl defensive lineman Richard Seymour missed the first two playoff games. And yet coach Bill Belichick was able to fill every one of these holes with a competent backup, even if it meant using wide receiver Troy Brown as a nickelback.

Not content to rely on such stopgap solutions, the Patriots have spent the off-season signing even more veterans to create their deepest roster yet. Most teams fill out the training-camp depth chart with undrafted rookies, but that’s not the case in New England.

For example, all eight defensive backs who played in last year’s Super Bowl are still on the team. So are two players who lost most or all of last season to knee problems: Tyrone Poole, who began the year as a starting cornerback, and Guss Scott, a third-round pick who spent his rookie year on injured reserve.

To these 10 players, the Patriots added three veteran defensive backs who were starters for other teams for at least half of 2004 – cornerback Duane Starks came in a trade, cornerback Chad Scott and safety Antuan Edwards in free agency. The Patriots also spent a third-round draft pick on cornerback Ellis Hobbs and a fourth-round pick on safety James Sanders.

As a result, the Patriots will bring to camp 14 defensive backs who either have NFL experience or were 2005 draft picks – 15 if you include Brown. Nine of those defensive backs have at least two years’ experience. By comparison, the Giants have only six defensive backs with at least two years’ experience, and the Jets only five.

Wide receiver is another example. David Patten’s departure for Washington opened one spot on the depth chart, but the Patriots signed two freeagent veterans, David Terrell and Tim Dwight. They also have 2004 fifth-round pick P.K. Sam, who spent most of his first season inactive but was specifically drafted as a developmental project.

At linebacker, the Patriots signed two players, Chad Brown and Monty Beisel, to try to make up for the loss of team leader Tedy Bruschi; now it turns out that Bruschi may be able to play this year despite the mild stroke he suffered in February. The Patriots even have three different players who were used as an NFL team’s primary kick returner last season: holdover Bethel Johnson and free-agent signings Dwight and Chad Morton.

Where are all of these players going to fit? The answer is that they aren’t. The Patriots have moved on to the next logical step. Not content to withstand injuries during the season, they have built up so much depth that they can withstand the inevitable injuries that come during training camp.

If a receiver or defensive back gets hurt during a preseason game, that spot on the depth chart will be taken by an experienced veteran, not undrafted rookie filler. And if nobody gets hurt during the preseason, the Patriots will just cut one or two of these veterans and escape relatively unharmed. Morton’s signing bonus was just $60,000, so that’s all the Patriots lose if he does not make the team. Dwight and Edwards received no signing bonuses, and cutting them before the season will cost the Patriots nothing (Scott did not receive a signing bonus either, but some of his salary is guaranteed).

The Patriots aren’t taking more players to camp than other teams; they’re just taking more players who are more than just fodder for the fourth-quarter of preseason games. It also doesn’t hurt that the Patriots prefer to offer good contracts to numerous quality veterans rather than a few gargantuan contracts to a handful of superstars, leaving very little money to fill out the depth chart.

Can other teams recruit a similarly deep pool of veteran backups? Some might, but not all can, because depth is a zero-sum game. Every veteran going to camp with New England also means one less veteran available to other teams. For example, although New Orleans offered Brown more money in free agency, the versatile veteran decided to return to the Patriots (an endorsement deal with a local bank, it turns out, will make up most of the salary difference). That meant that the Saints had to turn to their second option, free agent Az Hakim, which meant in turn that the Kansas City Chiefs – who wanted Hakim – had to turn to their second option, the erratic former Eagle Freddie Mitchell.

Of course, it’s not enough to simply accumulate veteran players; teams have to know how to use those players in a way that masks their declining skills and accentuates their remaining strengths.That’s where Belichick really excels, juggling multiple players at each position and using each one in the right situations. Other teams may copy the blueprints and try to collect extra parts like the Patriots have done, but only a coach who can turn the spare parts into a well-oiled machine can win the Super Bowl.

Mr. Schatz is the editor in chief of FootballOutsiders.com and the lead author of the forthcoming “Pro Football Prospectus 2005.”