Simple mathematics Sunday could prove just how valuable a healthy Mike Nelms really is to the Redskin special teams.

When Washington lost to St. Louis six weeks ago, 40-30, Nelms, one of the league's premier return men, did not field a kickoff or a punt.

He had a broken thumb. While he watched, the special teams endured one of their worst games in the last decade.

"The special teams gave up 14 points and we lost by 10 that day, so there's no question the special teams lost the game," Nelms said yesterday after the Redskins' final formal practice for the Cardinal rematch, at 4 p.m. at RFK Stadium. "We'd like to be the ones responsible for winning it this time."

If the special teams have success reversing some of those numbers, Nelms likely will one of the major reasons.

Since he got the cast off his thumb, he has brought back two punts for touchdowns and returned the thrill to the Redskin kick-return game. In the process, he has joined the league leaders in kickoff and punt returns as he tries to make the Pro Bowl for the second straight season.

"People probably didn't fully realize how important Mike is to our special teams," said Wayne Sevier, the special teams coach. "He's so talented and he contributes so much because he is so dangerous. But the guys also know he is good, so when he is in there, they block a little harder, just trying to give him a chance to break one.

"We appreciate the difference he makes. When he had the cast on, he averaged 5.1 yards on nine returns. Without the cast, he's averaging 16.8 on 14 returns, plus those two touchdowns."

Nelms' health is not the only factor in the special teams' improvement. They still have occasional lapses, but even with the loss of captain Clarence Harmon with a fractured shoulder, the units are much more consistent and reliable.

"We haven't had to shuffle personnel as much as we were doing," Sevier said. "That's helped. We've also added some new players, like Dallas Hickman, Quentin Lowry, Pete Cronan and Charlie Weaver, who are good special teams players. And we are just more fundamentally sound. We are fulfilling our assignments better. We've settled down.

"But we have to play well this week. In my rankings of special teams, St. Louis is No. 2 in the league. They are the best special teams we are going to play all season, even better than the Eagles."

The Cardinals rank among the top three teams in the NFC in kickoff and punt coverage. Carl Birdsong, their rookie punter, is second in net average (38.2) and third in gross (43.1). Kicker Neil O'Donoghue already has scored 50 points, making 11 of 17 field goal attempts, and could become the first Cardinal to score 100 points since 1967.

But the best of the Cardinals' special team players is the smallest, rookie Lyvonia (Stump) Mitchell, a ninth-round pick from The Citadel.

Mitchell, who is listed at 5 feet 9 and 188 pounds, returned one punt 50 yards for a touchdown against the Redskins and had a 35-yard kickoff return. He was responsible for 138 return yards, even though he left the game with an injury.

"Mitchell really put on a show that day," Nelms said. "He was impressive. It's something we just can't let him do again."

The contrast in styles between Nelms and Mitchell is just as revealing as the differences in their size.

Nelms (6-1, 190) relies heavily on an uncanny instinct to relax when he is about to be tackled. Instead of fighting the blow, he goes with it, waiting until he can break free.

Mitchell relies more on quickness and the skills he has developed from years as a running back in high school and college.

"I've just experimented with different approaches the last few years," Nelms said. "I became a full-time return man in 1979 (in Canada). I knew I had the job and no one was going to take over, so I could settle down, study films and find out what works best." Nelms has learned that a tackler lets up slightly when he feels he is in the process of dropping the runner.

"It's a feeling a guy gets when he thinks he's won the battle," Nelms said. "I decided not to fight him, to go strength against strength. Instead, I give. I let him have a dead leg, so to speak, let him think he's got me, but I keep my balance at the same time, and then I can pull away."

That's why, according to Nelms, he emerges from the middle of a pile of tacklers, and twists and turns for extra yardage.

"Sometimes, when I see it's the only way, I'll meet someone head on, but I think the reason I've never been seriously injured returning kicks is because of my style. It's not something that I've had to force."

But Sevier says that Nelms' success also can be attributed to his deceptive running style.

"He's so darn strong, much stronger than he looks," Sevier said. "And he just doesn't look like he is going very fast. Maybe it's because he is so smooth.

"He does everything subtly. Tacklers don't think they are being faked out and suddenly, he's by them. And they still haven't figured out what happened."