Which playoff teams won't repeat?

They call the NFL the "Not For Long" sport, and with good reason.

Since 1998, the average turnover rate for playoff teams is 6.14. Five to eight teams that made the playoffs one year won't make it the next. Since 1996, no fewer than five teams a season have failed to repeat. Longtime NFL commissioner Pete Rozelle called it parity. Teams acknowledge the tough chances of repeating as playoff teams as reality.

Unless a team has an elite quarterback to navigate the tough schedule that usually follows a playoff season, coaches can't plan for repeat trips to the playoffs. Atlanta (Matt Ryan), Baltimore (Joe Flacco), Green Bay (Aaron Rodgers), New England (Tom Brady), New Orleans (Drew Brees), the New York Giants (Eli Manning) and Pittsburgh (Ben Roethlisberger) are among the 2011 playoff teams with the best chances of repeating. Peyton Manning kept the Colts at a playoff level for 11 of 12 years.

But let's look at a couple of examples of teams that lacked that quarterback. The Chicago Bears have had great structure with Lovie Smith as their coach. He has installed a Cover 2 defense and filled it with good, smart athletes. Since 2004, the Bears are 71-57 and have been to a Super Bowl. Nevertheless, Smith has been to the playoffs three times and repeated only once. The Bears had a three-year playoff drought from 2007 to 2009.

Though many don't like to admit it, schedule is everything for teams without dominating quarterbacks. In the Bears' three playoff seasons, their schedules ranked among the 10 easiest in the league. In 2005, the Bears rode the league's fourth-easiest schedule to an 11-5 season. They won 13 games the next season and went to the Super Bowl with the league's easiest schedule (a combined .430).

In 2007, the Bears played a .543 schedule and dropped to 7-9.

Marvin Lewis and the Bengals have enjoyed three trips to the playoffs under his leadership. They had the ninth-easiest schedule in 2005, the 12th in 2009 and the 13th last year. In his first two playoff seasons, Lewis had an elite quarterback, Carson Palmer. But the schedule went to .535 in 2006 and .582 in 2010. The Bengals fell to 8-8 and 4-12 in those two seasons.

For predictions, I use a .20 difference on a schedule as an adjustment for wins and losses. If the schedule is .20 tougher, you add a loss. If it's .20 easier, you add a win.

So which five teams should be worried about not making the playoffs?

1. New Orleans Saints: Even though Brees is the quarterback, he's unsigned and unhappy. The bounty controversy takes away defensive end Will Smith for four games and linebacker Jonathan Vilma for the season. Head coach Sean Payton is gone for the season, and interim coach Joe Vitt is out six games. The schedule is another problem. In their past three trips to the playoffs, the Saints played the easiest schedule twice and the seventh-easiest schedule in 2010. Their schedule goes from .441 last year to .504 this year (a three-game difference). The NFC South is much tougher now with Cam Newton in Carolina and the Tampa Bay Buccaneers' big splash in free agency.

2. New York Giants: Repeating as Super Bowl champs is hard, but is it crazy to project that a Super Bowl team won't make the playoffs? Bear with me for a second. The Giants won nine regular-season games last year and didn't take full advantage of playing the NFC West, which has been the league's worst division. The Giants face the NFC South and the AFC North this fall and have the league's toughest schedule. They go from a .520 to a .547, which could cause a one-game drop. The Giants followed their first Super Bowl victory over the Patriots with an easier schedule and went 12-4. They had a harder schedule in 2009 and missed the playoffs.

3. Denver Broncos: Even if he throws just short and intermediate passes, Peyton Manning could be good enough to get the Broncos to 10 wins. Still, he's fighting tough odds. The Broncos were 8-8 with a .520 schedule. Their schedule gets a game tougher at .543, second toughest in football. That means Manning has to be worth three wins to get the Broncos to 10 wins.

4. Cincinnati Bengals: It's not the schedule in this case. The Bengals go from a .492 to a .500. The problem is the division. Until the Bengals show they are better than the Steelers and Ravens, they are fighting for the sixth seed. A team from another division with an easier schedule has a better shot.

5. Detroit Lions: The Lions have emerged from an 0-16 team to a playoff contender. The Packers are still the class of the NFC North, but I think the Bears had a better offseason and will get the wild-card spot the Lions claimed last year.

And which five teams that missed the playoffs last season could make it this season?

1. Philadelphia Eagles: Andy Reid and the front office rewarded some of the team's best young players, which should settle the locker room and cure the underachieving problems of last year. The Eagles should win the NFC East.

2. Chicago Bears: The additions of Brandon Marshall and Alshon Jeffery give Jay Cutler a chance to get back into the elite quarterback class. If that happens, the Bears will edge out the Lions for a playoff spot.

3. Buffalo Bills: They have a chance to be the league's surprise team. Their schedule goes from .520 to .473, a possible three-game improvement from a 6-10 season. Mario Williams and Mark Anderson add a pass rush. They have bigger, stronger cornerbacks and match up better against good offenses.

4. San Diego Chargers: If the Broncos do fail to defend the AFC West championship, the Chargers are in place to step back to the top of the division. If Philip Rivers cuts down his interceptions, he could wrestle the division away from Denver and Kansas City.

5. Dallas Cowboys: Jerry Jones knows the clock is ticking on the Tony Romo era. The Cowboys can slip into a wild-card spot if Romo stays healthy.