Forgive the Chicago Bears defense if it is a tad unfamiliar with the man playing behind the Washington Redskins' center Sunday at Soldier Field. Three times in the past four seasons, counting this NFC semifinal, the Bears and Redskins have played in the playoffs. Each time, the Redskins have started a different quarterback.

It was Joe Theismann in the 1984 playoffs, Jay Schroeder in 1986, and, this Sunday at 12:30 p.m., it will be Doug Williams. Theismann lost, Schroeder won and Williams has no decision. Not yet, anyway.

The common thread that runs through each quarterback and each game is the big play. Without making one in the '84 game, Theismann and the Redskins lost, 23-19. Because they made big play after big play in last year's playoffs, Schroeder and his teammates won, 27-13.

Yesterday, on the eve of one of the most important weekends of Williams' career, the 32-year-old quarterback sat on a couch at Redskin Park discussing -- you guessed it -- the big play.

"The Bear defense is to put pressure on the quarterback," Williams said. "It all depends then on who beats who. If we beat them, we get the big play. If they beat us, we don't."

Williams and Schroeder are considered tall, strong-armed, home run quarterbacks. Theismann, at 6 feet, is four inches shorter than the other two. He was known as a scrambler and darter. Possession passing was his specialty. But in his last two games against the Bears -- the one in the playoffs and a 45-10 loss in the 1985 regular season -- he fared poorly.

"That 1985 game just fell apart," quarterbacks coach Jerry Rhome said. "That was a mess. In 1984, they had a great fourth quarter. We should have won, but we just couldn't make the play, which was very unusual for Theismann."

"Joe was a good deep passer," Coach Joe Gibbs said. "But in the days Joe was playing there was a little different style of play by defenses. People today are more aggressive. You didn't get quite as many shots {to throw deep} when Joe was here as you do now."

Perhaps that was part of the problem Theismann had with the Bears. At the end of his career, Chicago was just beginning to emerge as a defensive force. Few outside the game knew the name Buddy Ryan. Theismann seemed to have problems with the Bears' pass rush. The Redskins tried the shotgun. It was shot down. Late in his career, Theismann also had trouble throwing the ball deep downfield. Seemingly nothing he or the Redskins did worked.

But then came Schroeder and the big play. The Bears blitzed often in last year's playoff game, and Schroeder burned the blitz for two touchdown passes to wide receiver Art Monk. All of a sudden, it appeared the Redskins knew how to beat the Bears. Perhaps it just took some time to get adjusted.

"With them, if you don't make any big plays, you're going to lose the game," Rhome said.

So now, the task of beating Chicago is passed to Williams, a man who played the Bears eight times in the regular season during his years with Tampa Bay, and beat them four times.

"Doug is big, he's hard to sack, he sees things and he gets that ball up," Gibbs said. "I think you'd be in real trouble playing a playoff game without a quarterback that can go deep."

Williams was sacked just 14 times in those eight games, a significant statistic because his offensive line wasn't very good. Gibbs used the term "slide" to describe how Williams eludes the pass rush. Williams says he goes on "feel."

"You know they're going to come," he said. "You know you have only a certain amount of time. It's sort of like a clock in your head going off, telling you to get rid of the ball."

Sometimes, the alarm goes off and you're caught holding the ball, Williams said. One time at Soldier Field, Williams had not been sacked in a long while when defensive end Dan Hampton got him.

"Hampton did his version of the Gastineau dance," Williams said. "I remember that very well."

Williams certainly fits Schroeder's mold, the quarterback mold that beat Chicago last postseason. The Redskins have placed their hopes on him. The strategy is simple: blitz and burn, blitz and burn.

"It's a guessing game," Williams said. "Who's going to out-guess who?"

Chicago Coach Mike Ditka is never too far behind Gibbs. In fact, in quarterback switches, he has stayed right with Washington.

It's true the Redskins have started three different quarterbacks in those three playoff games. It's also true that the Bears have done exactly the same thing.

In 1984, Steve Fuller was the starter. In 1986, it was Doug Flutie. Now, it's Jim McMahon.

Redskins Notes:

Wide receiver Clarence Verdin, who said earlier in the week that he isn't going to be activated for the playoff game, missed practice yesterday to be with his wife Carolyn, who underwent an operation in Texas.

Anthony Allen, the former replacement player who set the team record with 255 receiving yards against St. Louis in October, will replace Verdin on the roster, although Gibbs has not announced that yet. Allen, who played three seasons in the U.S. Football League and two with the Atlanta Falcons, has more experience than Verdin, who played two seasons in the USFL before joining the Redskins last season.

On activating Allen, offensive assistant coach Dan Henning said, "There are a bunch of reasons why, but the main one is we decided that was the way to go." . . .

No matter what weather the Redskins face Sunday, they've prepared for it. After two days in the bitter cold, they practiced yesterday on their slick artificial turf field, with several feet of plowed snow piled at the sides. Gibbs said that despite the weather conditions, the Redskins have been able to practice everything they wanted to.