Seattle ? Anybody can win.

That’s the beauty of the NFL. At least that’s the party line. Or the parity line, since that’s what we’re talking about.

Just one problem. That means everyone loses. That’s by design, since everything from the NFL’s salary cap to the draft order to the nuances of the schedule are designed to promote turnover at the top. San Francisco’s victory over Seattle on Thursday was the 86th time in 209 NFL games this season the underdog won outright.

Parity, gotta love it.

Except at some point parity gets in the way of enjoyment. One of the best parts of the NFL season is watching the wheat get separated from the chaff through the regular season, building toward the excitement and uncertainty of a playoff meeting. Only now, the playoffs become contests between two teams that have spent the past few months repeatedly stubbing their toes.

The playing field is level, all right. The question is how far everyone is above the gutter. The league is full of fans fully aware of their team’s warts, with their only consolation that the rest of the league isn’t that far ahead.

The Patriots won three of the past five Super Bowls. Their coach is a sweatpants-wearing savant, the quarterback plays with Joe Montana’s coolness, and their December success has become as predictable as Christmas.

New England had won 12 of its past 13 games in December before going to Miami last week, where the Dolphins hung a doughnut on the Patriots, winning 21-0. Suddenly things look grim for the Patriots, who are an injury or two away from having to line up Pat Patriot at wide receiver. Even Tom Brady and Bridget Moynahan hit splitsville.

Tough times, tough times. Astronomers could be consulted given the number of falling stars around the league.

The Colts have the most consecutive playoff berths in the league, and last week they gave up the second-most rushing yards in any NFL game since 1970, losing for the third time in four games. The Seahawks have lost three in a row within a division that is downright dreadful.

The salary cap was instituted in 1993, changing the league’s landscape, and the results are now evident. Twenty-six of the league’s 32 teams have made the playoffs at least once in the past four years.

That means the top of the standings is like a treadmill. You run as hard as you can and stay stuck in one place.

Chicago is 11-2, first in the NFC, yet plenty believe it needs to change its quarterback. San Diego is 11-2 and leading the league in scoring, but the Chargers have a coach who is 5-12 in postseason and hasn’t won a playoff game since 1993.

Parity was supposed to end the dynasties and bring hope to even the darkest little hamlets of the league. That’s a good thing.

The problem is that it may have worked too well. This is a season that dulled the shine off everything. Excellence has been eroded. And now, the Seahawks’ greatest hope is that while they might not be very good, no one else is, either.

Parity, gotta love it.