Oh, How the NFL's Mighty Has Fallen

What a difference a year makes in the NFL.

Last December, the New York Giants and Carolina Panthers—the NFC's two top teams in 2008—met on a Sunday night with the No. 1 overall seed on the line. But when the two teams battle on Sunday afternoon, in the Giants' regular season finale at the Meadowlands, only the home team has a playoff spot in sight.

The 8-6 Giants are a game behind Dallas in the wild card race and have the season series in their pocket after a pair of wins over the Cowboys.

Yet it was only last season when New York was the conference's top seed with home field advantage throughout the playoffs and looked primed to defend its Super Bowl title. Then, the Plaxico Burress fiasco left Eli Manning and the Giants offense without a big target, and they were ousted quickly by Philadelphia in the divisional round.

On the other side, the Panthers are 6-8 and only a shadow of their 12-4 selves from a year ago when they hosted a divisional playoff game against Arizona and were embarrassed in the 20-point defeat, caused by seven turnovers. And since Jake Delhomme's destruction in January, Carolina has suffered a giant fall in the NFC with a mark below .500—nowhere near the division's elite in New Orleans.

The Panthers' fall from grace marks an emerging trend in the NFL that's seen a handful of top teams take a plunge in the standings over the course of one season, stemming largely from parity. Teams that reach great heights suddenly play a tougher schedule the next season, while division and conference rivals can take a giant leap forward, culminating in a disappointing result, which four teams in particular have suffered in 2009.

Amazingly, the top seeds that earned first-round byes a year ago—the Giants, Panthers, Titans, and Steelers—have stumbled through their schedules and could all miss the playoffs by season's end on January 3. Each of the four disappointments haven't played the same kind of smash-mouth football that led each team to best in their respective conferences.

The fact that three of the four teams—aside from Pittsburgh who won the Super Bowl—were eliminated at home in the divisional playoffs perhaps foreshadowed struggles this season.

Clearly, New York has been the best of the pack to this point in the season with a shot at the playoffs still. But a depleted secondary and lack of a pass rush on defense largely resulted in a horrendous four-game losing streak that quickly erased a 5-0 start.

Last year, the G-Men started 11-1 and secured the first overall seed with that victory over Carolina on Sunday Night Football . But they have since fallen from the top ranks of the NFC—as have the Panthers.

In the AFC, Tennessee was the best team in football last fall with a 10-0 start to the season before Brett Favre and the Jets knocked them from the undefeated ranks. The Titans, though, dominated the Steelers 31-14 at home in the AFC's battle for first in late December—fittingly on the same Sunday New York beat out Carolina.

The monstrous win over Pittsburgh, and the subsequent stomping of the Terrible Towel by linebacker Keith Bullock, gave Tennessee home field advantage. However, it wasn't much of an advantage at all in the playoffs, as they were narrowly beaten 13-10 by a red-hot Baltimore team, which earned a trip to Pittsburgh for the AFC Championship game.

In 2009 however, it was a disastrous start for the Titans, who lost their first six games of the year. And despite winning the next seven of eight with Vince Young under center, they won't be back in the postseason after Friday's blowout loss to San Diego, going from 13 wins to a .500 record in the span of a season.

For their part the Steelers, the only top team out of the bunch to win a home playoff game, have suffered through an injury-riddled season with the loss of safety Troy Polamalu (knee) on defense and the absence of Ben Roethlisberger (concussion) for a game-plus.

A 12-4 record, which earned Pittsburgh the No. 2 seed in the AFC and paved its Super Bowl run, has been followed by a major collapse in the second half of 2009.

A five-game losing streak, including embarrassing defeats against the Chiefs and Raiders, knocked the defending champs from a first-place tie in the AFC North at 6-2 to out of the playoffs, which now would be a Christmas miracle in the final two weeks of the regular season. Despite the comeback victory over Green Bay, two wins are in order against the Ravens and Dolphins for Pittsburgh even to have a shot.

So, if the playoffs started today, all four top seeds from 2008 (which combined for 37 wins) would be watching the postseason from their living rooms. Tennessee and Carolina have already been eliminated from contention, while Pittsburgh and New York are hanging by a thread in the AFC and NFC wild card races, respectively.

It just points to the amount of parity in the NFL. Aside from the league's bottom feeders, it can be a quite the sudden plunge from one season to the next for any elite team.