When Joe Theismann saw a reporter approaching his locker last week for an interview, the Redskin quarterback greeted him with mock anger.

"When we were losing, every week you want to talk to me," Theismann said. "But when we win, where are you? You haven't been around for days."

Then he laughed.

Ever since the Redskins broke a five-game losing streak and started a steady climb toward respectability, Theismann has found his football life much more enjoyable. He's so relaxed that, for once, he doesn't seem outwardly bothered by this annual trek to his home state, where the Redskins play the New York Giants Sunday at 4 p.m. (WDVM-TV-9).

Theismann never has played very well in the Meadowlands, and had a poor day earlier this season against the Giants in RFK Stadium. New York prevailed that day, 17-7, because of a partially blocked punt and a Theismann fumble that was returned for a touchdown.

But now, no one is talking about Theismann's early erratic play.

And there is no more talk about Theismann being benched for rookie Tom Flick, or about the veteran quarterback's indecisive passing. Instead, he has settled into a quiet (for him) pattern that should, barring injury, produce the finest statistical season of his career.

Theismann's continued efficiency is essential for the Redskins to have any chance of beating the 5-5 Giants, whose defense is even stronger than usual this season with the addition of rookie linebacker Lawrence Taylor. The Giants are favored by two points.

The Redskins could get a break if linebacker Harry Carson, the Giants' leading tackler, cannot play. Carson has a bruised shoulder and is considered "very questionable" for the game.

Theismann, meanwhile, has completed 62 percent of his passes (76 of 122) for 900 yards, five touchdowns and just four interceptions over the past five weeks, when the Redskins have compiled a 4-1 record and a three-game winning streak. In the first five games, he had nine passes picked off.

Theismann credits his improved consistency to a healthy right thumb, which he hurt in the opener against Dallas; an offensive line that no longer is changing weekly because of injuries; the emergence of a running game that has made play-action passes more dangerous, and Coach Joe Gibbs' decision to reduce his passing calls and go with a one-back, two-tight end offense.

"For the first five weeks, we were changing everything every week, calls, formations, players, what have you," Theismann said. "Now we are doing the things that we feel comfortable with. It shows, we are executing better and the mental mistakes have been reduced. We are doing things we should have been doing earlier, but maybe you have to go through growing pains with a new coach and new players before you can settle in."

Statistics dramatically show the difference in the Redskins from the first five weeks to the next five. They have turned the ball over much less (nine compared to 21), had far fewer penalties (26 compared to 41) and had more takeaways (19 compared to six).

"But you have to remember that the Giants are better, too, since we played them in September," Gibbs said. "They've settled into a very fundamental 3-4 defense that does nothing fancy and their offense has developed a lot."

That New York offense, however, may not be functioning completely for this game. Quarterback Phil Simms will start, but he still is hindered by a groin pull. Halfback Rob Carpenter, who has given the Giants a much-needed running game since coming over from Houston, may not play because of a hip injury. And center Jim Clack will start after returning from retirement earlier in the week.

Washington has made five changes in that defense for the Giants, including an almost completely new left side, where linebacker Brad Dusek, cornerback Jeris White and end Mat Mendenhall will start. Dexter Manley, replacing Karl Lorch, moves into right end and Monte Coleman switches from left to right linebacker. Wilbur Young, who had been benched, also will be used for the first time at end in pass rushing situations as the Redskins try to get increased pressure on the quarterback.

With Virgil Seay out because of a hamstring pull, Terry Metcalf will get his first start at wide receiver.