Four reasons 16-0 will never happen in the NFL

If the first month of this season has taught us anything, it's this: There are a handful of good football teams, followed by a slew of squads in the mediocre category. In fact, there is such an early disparity between the haves and have-nots that some folks have started whispering about the chances of a team -- namely those high-flying New England Patriots -- going undefeated.

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Please don't buy into that line of thinking. As good as the Pats look, perfection isn't a realistic option. The same goes for the other remaining undefeated teams. The Colts teased us two years ago with a 13-0 start and we all know how they wound up. The Dallas Cowboys are racing past opponents with an offense that runs on jet fuel but they're still coached by a man named Wade Phillips (career record: 49-35). Then there are the Green Bay Packers, the feel-good story of the first four weeks. Nobody saw that coming, not even the faithful who reside in Wisconsin.

It's simply harder to be perfect in the NFL's current parity-driven environment, which is why the 1972 Miami Dolphins, the only team to go undefeated in a season, should never have to worry about an end to the annual celebrations of their historic achievement. As one NFC personnel director said, "If you put a gun to my head and asked me to make a choice, that's one thing I'd bet against ever happening again. Is it possible for somebody to go undefeated? Sure. But it's a pretty hard feat to pull off." Here's why:

1. Depth

The first thing a team needs for a perfect season is a near-perfect roster. Those are pretty hard to come by in today's NFL, primarily because of one reason: the salary cap. Ever since the league adopted a hard cap in 1994, it has become increasingly difficult for franchises to stockpile the kind of talent that propelled the Dolphins to their magical season (Miami had six future Hall of Famers on that team).

"You definitely don't see the powerhouse teams that you saw two or three decades ago," said Washington Redskins running backs coach Earnest Byner, who played on the 1991 Redskins team that started 11-0 and won Super Bowl XXVI. "Unlike in the 1970s and 1980s -- when teams like Pittsburgh, Dallas and Miami had a ton of players -- there's a greater balance of talent now. That just makes it harder for one team to dominate."

Even if you have a slew of potential Canton candidates, there's always a chance of injury -- and finding experienced backups also is more difficult today. Consider that the 1972 Dolphins won 11 games with Earl Morrall filling in for injured starter Bob Griese at quarterback. There's no way a team can go undefeated with that type of setback today, not even two teams as balanced as New England and Indianapolis.

"Could you imagine what would happen if the Patriots lost Tom Brady or the Colts lost Peyton Manning?" one AFC executive said. "They'd both be done."

2. Defense

Having a great defense is a vastly underrated aspect of enjoying a perfect season. That's because every team that has made a run at the Dolphins' record has watched its defense unravel at the end of its winning streak.

It happened to the 1985 Chicago Bears, who won 12 straight games until their vaunted defense ran into Dan Marino and the Dolphins' quick-strike passing attack. It happened to the 1998 Denver Broncos, who opened that season with 13 wins before the New York Giants exposed their ordinary defense in a 20-16 loss. And it happened to the 2005 Colts, who also started 13-0 before losing to a San Diego team that opened that game with 16 unanswered points.

There are two points to be made here: (1) The NFL has bent its rules so much to favor offenses that it's difficult to build great defenses, and (2) the cost of investing in a potentially great defense means there is less money to spend on offense, thus forcing teams to become somewhat one-dimensional.

Consider this year's 4-0 teams. The Colts and Patriots have good defenses but neither is dominant. The Packers are greatly improved defensively but still rank 19th in yards allowed. The Cowboys already have injury issues to key players. You can expect each of those defenses to be lit up at some point this season.

3. Distractions

The toughest part of pursuing a perfect season? The hype it creates.

Win 10 or so consecutive games and suddenly a media circus develops. And if a team isn't careful, swelled egos and misplaced priorities can develop in the locker room -- maybe not enough to unravel a season but certainly enough to cause a one-game stumble.

Take the '85 Bears. That team actually made plans in advance to shoot its infamous "Super Bowl Shuffle" video on the day after the Monday night game in Miami. Did the Bears' cockiness play a part in that 38-24 loss? Were they worried more about the video and less about Marino? Tough to say. But even a small distraction can be exploited by a strong opponent.

Chasing a record means finding yourself under a bigger spotlight -- and not every player puts it in the proper perspective.

"The big thing you have to always wonder about in those situations is how the younger guys will handle the attention," Byner said. "You know the older guys are usually going to take things one day at a time -- which is how you win so many games in the first place -- but younger guys can start buying into everything that's being said about them. And once that happens, you're in trouble."

4. Disinterest

Let's face it: No team really talks about going undefeated. It only happens if everything else works out.

"Most teams start their season talking about winning a division or securing home-field advantage," one NFC personnel director said. "And when you're playing for those things, you're usually focused every week. But once you reach those goals, everything changes a little."

Added Cardinals running back Edgerrin James, who played seven seasons with the Colts: "When I was in Indianapolis [in 2005], we could've gone undefeated but we also had to ask ourselves what we were playing for -- was it to win a championship or to have a perfect season? It would've been one thing if we had a team that was competing with us for something but we had our division wrapped up by Week 13. It just wasn't worth the risk."

That risk James referred to is injury. No team wants to enter the postseason with a banged-up star player who was injured in a meaningless late-season game. After all, they don't hand out trophies for going 16-0 in the regular season. Discussing the 1972 Dolphins may be fun, but that team isn't motivation for today's players. "I bet you most of the players in this league couldn't name two players off that '72 Dolphins team," one AFC coach said.

What is apparent is that this year's remaining undefeated teams are thinking along the same lines. It's too early for them to be talking perfection, but if they reach a point where it is within their reach, they'll have to decide how they feel about it. And right now, it's a given that they'd be less interested in chasing history and more focused on what it takes to hoist a Lombardi Trophy at the end of the year.

"If some team wants to go undefeated, they better have some great backups and a real easy schedule down the stretch," James said. "Because the more you win in this league, the more you want to keep your guys ready for the postseason."

Playoffs, not perfection, is the goal. Maybe that's why the '72 Dolphins will keep on celebrating every year.

Jeffri Chadiha is a senior writer for ESPN.com.