In the early 1960s, two NFL teams enjoyed exclusive national television contracts. The Cleveland Browns had a deal with CBS and the New York Giants were affiliated with NBC. With an assist from young commissioner Pete Rozelle, Browns owner Art Modell approached Giants owner Wellington Mara with a novel concept for its time: revenue sharing.

	Art Modell, who once sacrificed his team's wealth for the betterment of the NFL, finally won a Super Bowl title in 2001.

Both Mara and Modell agreed to forfeit their exclusivity for the good of the league that had yet to grip the populace in the manner of, say, the national pastime. And while this decision ultimately cost both men hundreds of thousands of dollars, it was the right thing to do. For today, football is the America's preeminent sport by most important measures. Their investment has repaid itself over many, many times.

"We are rich, staunch Republicans," Modell likes to say, "who are socialistic in our business practices."

Modell moved the Browns to Baltimore after the 1995 season under less-than-altruistic circumstances, but the league remains the model of parity. Which is why you will never see teams dominate the league like they used to back in the day. Consider:

The Green Bay Packers won five championships in seven years (1961-67), the Pittsburgh Steelers won four titles in six years (1974-79), the Dallas Cowboys won three times in four years (1992-95) and the 1997-98 Denver Broncos were the last team to repeat. Five, four, three, two … What kind of shot do you think the New England Patriots have of repeating? About the same as the St. Louis Rams and Baltimore Ravens before them. Slim and none. So, is there a trend here?

"According to the parameters of the game, the nature of the game as it's played today, you can't keep a team together," said Bill Walsh, former coach, general manager and now a consultant for the San Francisco 49ers, just one of two teams (Dallas being the other) to win five Super Bowls. "The Yankees can do it with money and tradition, but it's truly tough in football because of the numbers you need."

In 1993, labor peace between the owners and players brought a new system of free agency. For the first time, teams would operate under a salary cap. With the NFL salary cap at $71.101 million for the upcoming season, most teams will pay a dozen or so players with the lion's share of that amount, say 60-70 percent. That means there will also be a dozen players making the minimum wage; for first-year players that number is $225,000. Essentially, it comes down to a team's best dozen players versus the other team's best 12.

And when teams begin to win, their players are coveted by other teams. That makes the cost of free agency greater for winners.

"I think a veteran team can look to, at the most, three years of sustained viability as a true contender," said Carmen Policy, the Cleveland Browns' president. "Staying on top is not only more problematic, it's impossible."

	Jim Kelly and the Buffalo Bills don't want your pity after failing to win in four Super Bowls.

Bill Polian, who constructed the great Buffalo Bills teams that reached four consecutive Super Bowls from 1990-93, said he believes that kind of sustained excellence is no longer possible.

"The beauty of this system is that even though it has a lot of drawbacks, it's a great equalizer," said Polian, now the Indianapolis Colts president. "By its nature, it erodes good teams. Teams can't stay long. Green Bay is an example. They made two straight Super Bowls, but the Packers were clearly eroded by the cap. It gives everybody a chance to be successful, a chance to feel they can be successful."

An example of the NFL's field-leveling rules can be seen in the extraordinary rise of the Jacksonville Jaguars and Carolina Panthers. Expansion teams in 1995, they actually reached their respective conference championships in the second year of existence. They got their not only because their management was shrewd, but because the league gave them liberal free agency and drafting advantages.

In the NBA, halfway decent teams still can wind up with the first overall pick. When a team wins the Super Bowl in the NFL, it drafts last. Even a brilliant personnel operation can't overcome odds like that forever.

It's worth noting that the Packers, Steelers, 49ers and Cowboys were all dreadful before they righted their respective ships by addressing their (gaping) holes through the draft. Bart Starr, Terry Bradshaw, Joe Montana and Troy Aikman all arrived via the draft and three of them are already in the Hall of Fame, with Aikman soon to follow.

	There is little distance between destiny and defeat, as the Titans' Kevin Dyson and Ram's Mike Jones can attest.

The NFL's system of parity has paid huge dividends in attendance and television ratings. No one -- outside of the Cincinnati Bengals -- stays horrible forever. In the past five years, there have been 20 slots available in the conference championship games. In that time an amazing 16 different teams reached the NFL's final four. The only repeaters: the Denver Broncos, Oakland Raiders, Minnesota Vikings and St. Louis Rams.

The Rams are the team that currently enjoys that narrow window of opportunity. They haven't exactly been dominant, but they have been close by today's standards. They won Super Bowl XXXIV, 23-16 over the Tennessee Titans -- by a matter of inches on the last play of the game. They reached Super Bowl XXXVI, only to be stunned 20-17 by the Patriots. In between, however, the Rams failed miserably. They went 10-6 and lost to division rival New Orleans in the NFC wild-card game, 31-28. Later, the Saints were pounded by Minnesota (34-16), who were in turn crushed (41-0) by the Giants, who were in turn destroyed (34-7) by the Ravens of Art Modell.

Apparently, what goes around comes around. Parity eventually smiled on the man who helped bring the NFL into the age of socialism.

"The idea that you could have the 49ers, the Bills, the Redskins, the Cowboys, ..." Polian said of some of the greatest teams in NFL history. "No longer."

Greg Garber is a senior writer for ESPN.com