WE KNEW IT all along -- even if better judgments were suspended all around town for one last desperate day: Never count on the Dallas Cowboys. Rooting for them was awkward enough, and all the crocodile cheers for America's Team from America's Capital couldn't save the Redskins' mortgage for the playoffs. There in front of their TV screens like the rest of us, Coach Joe Gibbs and his exceptionally battered charges were reduced to helpless onlookers, buoyed by a halftime high and then unceremoniously stripped of rank in short order. So, for the fans, it's back to those seasonally neglected weekend responsibilities -- but not with too heavy a heart.

There's much to admire in the 'Skins of '85, who turned in their grittiest performances in the worst of conditions -- and wound up with the same win- loss record as the Cowboys, 49ers and Giants, losing out only because of other elimination factors. True, trend-seekers can point to the stats for a disturbing pattern: Super Bowl champs in 1982, conference champs in 1983, division champs in 1984 and playoff discards in 1985. Still, this team did go on from a 5-5 record to win five of its final six games with sharp play from young talent.

The not-so-secret word for next year is youth; in this business it never yields for long, and always wins eventually. Much as Mr. Gibbs respects what the big stars of only months ago did for the team, he is not about to turn next year's summer camp into a geriatric clinic. The players, too, are hardly oblivious to the cold facts of football life -- and what comes after it.

What comes through every season in Washington is the exceptional caliber of the Redskin players as human beings who care about and contribute generously to this region. They do more than token charity appearances, and they do it with warmth, good humor and impressive dedication. That's got a little something to do with why the Redskins are such an exceptional and important unifying influence on people throughout Greater Washington. Once again, hail and farewell.