The aged and immobile quarterbacks of the National Football League are getting knocked off one by one.

Atlanta's Steve Bartkowski, 32, is out for an undetermined length of time with a knee injury. And once he returns to the Falcons (0-6), Bartkowski might not be able to unseat his replacement, 23-year-old David Archer.

San Diego's Dan Fouts, 34, suffered torn knee ligaments two weeks ago and, although there are indications he might return soon, it's unlikely he'll play this week. If not, this would become the third consecutive season in which Fouts has missed at least three games in a season due to injury.

The Raiders' Jim Plunkett, 37, separated his left (nonthrowing) shoulder and might not return.

Is the immobile quarterback becoming outdated?

"With so many situational defenses, you get more blitzes now, so you have to have a quarterback who can move," George Young, Giants general manager, said at league meetings today in New York. "But, no, I don't think we've got a trend. In 1970, Terry Bradshaw was the first big, strong, mobile quarterback. There was Fran Tarkenton, too.

"It's just that older players, whether they are quarterbacks or not, tend to get hurt more. Plus, look at (Miami's) Dan Marino. He's not that mobile and look what he's done."

New York Giants quarterback Phil Simms has thrown a total of 98 passes for 945 yards and four touchdowns over the past two games -- and the Giants lost both games . . .

A 49ers fan wrote a letter to quarterback Joe Montana earlier this season, noting that the San Francisco offense was performing like "Mickey Mouse" and wasn't worth paying to see. Montana sent a handwritten letter back to the fan, who then sent Montana's response to the local newspaper.

The paper, naturally, printed Montana's response. Montana wrote that the 49ers deserved more loyalty from their fans. He also wrote, "I suggest you subscribe to the Disney Channel if you like Mickey Mouse . . . "

If you're trying to figure out why the Jets are 5-1, consider that the offense has committed only two turnovers during this five-game winning streak. Ken O'Brien, the fifth quarterback selected in the first round of the 1983 draft (Miami's Marino was the sixth), has six scoring passes and one interception during the streak.

Former Redskins update: In Atlanta, wide receiver Charlie Brown has missed the past two games with broken ribs. He's caught 14 passes for 197 yards and one touchdown. Running back Joe Washington has run 14 times for 57 yards and has caught 21 passes for 159 yards for Atlanta.

Rookie cornerback Tory Nixon, the Redskins' top draft pick in 1985 who was traded to San Francisco, is playing on the special teams and, occasionally, plays in nickel (five defensive backs) situations. He was beaten for a 34-yard gain by Chicago's Willie Gault Sunday.

The Bears' 46-Defense, which deploys four linemen, one linebacker and six defensive backs, has been the league's most dominant unit over the past two years.

Quite often, the Bears' alignment places eight defenders near the line of scrimmage and five of them rush the passer. This forces the five offensive linemen to block man to man, thereby opening blitzing lanes. Cornerbacks are often left in man-to-man coverage.

"It's the unorthodox style that creates problems for offenses," said Dan Hampton, Chicago's all-pro defensive tackle. "The secret is not having great cornerbacks. We only have good ones, not great ones like the Raiders have. (The 46-defense) shelters coverage, really. It takes great versatility for the line and linebackers to rush the passer and to play the run, too."