From left, Leon Washington, Thomas Jones (20) and Jerricho Cotchery helped the Jets rose above the Patriots in November and that overtime loss was a major factor why New England missed the playoffs.

The Journal / Gretchen Ertl

Third-and-15.

The play that may have made the difference.

It isn’t often that a team’s season can be boiled down to one play, one moment, but that may be the case for the New England Patriots.

Because third-and-15 may be what separated the Patriots from the playoffs and the abrupt end to their season they experienced on Sunday.

On Nov. 13, their Thursday Night Football showdown with the New York Jets, the Patriots had just completed an edge-of-your-seat comeback. Matt Cassel drove New England 62 yards in 63 seconds, capped by an incredible pass to Randy Moss, who stretched to his full 6-foot-4, his toes amazingly stuck to the turf as the rest of him lunged over the sideline to pull in the ball.

All the momentum was on the Pats’ side.

They lost the coin toss for overtime, but Pierre Woods dropped Brett Favre for a five-yard loss on New York’s first play, and a pass to Leon Washington fell incomplete.

Third-and-15 for the Jets, from their own 15-yard line.

We all know what happened: Favre completed a 16-yard pass to tight end Dustin Keller, the Jets went on to kick the game-winning field goal and took over first place in the AFC East.

Cassel threw for 400 yards and ran for 60 more that night, with three touchdowns, no interceptions, stayed level-headed, and was the anti-Favre as he brought his team back from a 24-6 first-half deficit. Cassel stepped out of Tom Brady’s considerable shadow and a major chance was lost.

A few days after the game, New England defensive coordinator Dean Pees blamed a blown coverage for the completion to Keller.

But it couldn’t be undone then, and it can’t be undone now. And that third-and-15 is quite possibly the reason the Patriots find themselves as outsiders in the postseason for the first time since 2002.

New England was caught off-guard by Miami’s unveiling of the Wildcat in early September, and lest we all forget, the team was still dealing with the reality of Brady’s season-ending injury and the transition to Cassel as starter. Three or four defensive mistakes in San Diego — glaring as they were — made the difference against the Chargers.

Jabar Gaffney’s drop in Indianapolis wasn’t the biggest problem against the Colts; it was certainly the most glaring, but there was also the matter of allowing the Colts to convert six of 10 third-down chances, with all of those conversions coming on scoring drives.

And a month ago, Pittsburgh was simply a better team than New England.

That Jets game, however, is a different story. New York was reeling after having giving up its considerable lead, and had the Patriots gotten the ball back, it seems difficult to imagine that they would not have put points on the board given the way the offense was playing.

Make no mistake: That the Pats even posted an 11-5 record this season, playoffs or not, is an impressive feat and arguably marks Bill Belichick’s greatest season of coaching in a career marked with great efforts.

When Brady was hurt and Cassel, who had been spectacularly erratic in training camp and the preseason games stepped under center, the season became a giant question mark. Then Laurence Maroney went down. Then Rodney Harrison. Then Terrence Wheatley. Then Adalius Thomas. Then Pierre Woods.

It all seemed like too much to overcome.

And none of that takes into account the fact that Sammy Morris, Ty Warren, LaMont Jordan, Jarvis Green, Tedy Bruschi, James Sanders and Lewis Sanders missed at least two games because of various ailments.

But a week from now, a month from now, a year from now, when Belichick or his players reflect on this season and where it might have slipped out of their hands, there is likely one moment they’ll pinpoint.

Third-and-15.

smanza@projo.com