I started watching NFL football at the early age of 8. Since then, many seasons have passed and the records of teams have dramatically changed. Its lead me to believe in a theory I've found self evident in the NFL. To state it: Teams have cycles where they are Bad and then add players who make them good for about 5-8 years usually. As they hold on to the successes of past seasons, their players grow older and the surrounding team either becomes old with them or extremely younger. There are also transitional periods: From Bad to Average to Elite, for example. So allow me to show a couple instances that give evidence that supports the Theory.
Exhibit A: The Jacksonville Jaguars
The Golden Days: The Inaugural Season to 1999
The Jaguars were one of the quickest franchises to reach the playoffs after their first year as being a team. The Jaguars went to the AFC Championship in 1999 losing to the Titans for a third time. During this Era, the Jaguars had as many playmakers on defense (Tony Brackens, Donovin Darius, Kevin Hardy, Joel Smeenge, Jeff Lageman, Aaron Beasley) as offense (Mark Brunell, Stacy Mack, Fred Taylor, Jimmy Smith, Keenan McCardell, Tony Boselli, Leon Searcy). The Foundations of the Franchise were set down and the fanbase created. Waves of Teal were seen in all corners of the stadium, everything was good and no losing seasons could stop it. These were the glory days as the team played well but the future would not play out so well.
The Dissappointment of the Reckoning Years (2000-2008)
The old team was ripped apart by the chaos of the shuffling of a new NFL. The divisions were changed and the Jaguars joined by newcomer Houston, the Titans (The ex-Oilers), and the Colts. As some would describe the 2000 season as "Salary Cap Hell" as Tony Boselli, Seth Payne, Gary Walker and others were cast as sacrifices to the Cap so Houston could get them during their expansion year. Tom Coughlin was fired and the beginning of a long, painful time began. Horrible First round picks, in hindsight, were drafted leaving a team vulnerable to mediocrity. Shack Harris would all but screw us. We were pitiful and had our best season in 2007, though which lead to Superbowl-esque expectations that nearly killed the fanbase as it drowned in its high expectations. The unity and sellouts of the past would lead to blackouts and discussions of drafting more Gators in the first round. This period was a time of sadness as the Jaguars were bad in management and on the field.
The Revival of Jacksonville (2009-????)
Gene Smith was the catalyst of the current period in Jaguars history. Good drafting has lead to a entirely different Jaguars. The WR corps were dramatically culled and replaced, the non-existant pass rush reborn (hopefully), and the old replaced with the new. The Jaguars of 2009 were inconsistantly good as they were bad but upon looking at the youth, its understandable. The 2010 Jaguars should be more mature and more productive, hopefully leading to the team being Superbowl contenders in a couple years. Reconstructioning success is in process and the result should bring the Jaguars out of the cellar of the Mocked and #1 Draft pick contenders. With fans coming back into the Collective, the Jaguars must keep success flowing and not let any of this momentum falter. We cannot survive many more hits.
So in conclusion and with just one example of it, i believe the NFL works in cycles where every team will have its day no matter how short it is.