For four years, their string of successes has been attached to a yo-yo. Strange team, these Atlanta Falcons.

In 1978, they were a wild-card 9-7; their fans called them, "The Grits Blitz."

In 1979, they were 6-10; the blitz was gone, the grits remained.

In 1980, they were 12-4, NFC West champions.

In 1981, they were 7-9, wondering what kind of geography places Atlanta in the west, anyway.

When rookie kicker Mick Luckhurst missed a 33-yard field goal in the final seconds of a 30-28, season-ending loss to Cincinnati last year, it didn't ruin Atlanta's playoff chances. The Falcons were already out of it.

"Watching the kick, I knew we were a better team than 7-9," said Leeman Bennett, the Falcons' coach since 1977.

"I just said to myself, 'I'm glad it's over. It's been a nightmare. Let's get to next year,' " said wide receiver Alfred Jenkins.

Luckhurst said, "At least we got a better draft pick out of it."

There are different memories of the Atlanta breakdown in 1981.

"We just had a big sag," said General Manager Tom Braatz.

"We came to camp last year trying to live off our press clippings," said Bennett. "What crept into us was the feeling that 1980 would be able to take us to the 1981 playoffs."

It didn't. Last year, Atlanta's offense scored 426 points, second to San Diego's 478. Steve Bartkowski threw 30 touchdown passes; Jenkins caught 13 of them. "And Bartkowski played six games with broken ribs," said Eddie LeBaron, the Falcons' executive vice president, who has the quarterback signed for another three years.

Consequently, the finger of blame points to the defense, which gave up 355 points, 18th-best in the league. The defense was painfully vulnerable to the pass, ranking 25th of 28 teams.

The turning point was the third game. NFL historians will note the Falcons beat San Francisco, 34-17 (making Atlanta 3-0), and that the 49ers lost only one more game that season and that Super Bowl XVI was not that game.

But what the Falcons' history book records is that this was the game in which defensive end Jeff Merrow and right outside linebacker Joel Williams were injured. Merrow, with a hamstring injury, missed five games; Williams, with a knee injury, missed six games and played the rest of the schedule like the Falcons flew their 1981 flag: at half-staff.

Losing the 6-foot, 215-pound Williams was the defensive deathblow. In 1980, his second NFL season, he had an NFC-high 16 sacks, plus three fumble recoveries and two interceptions. He is to the Atlanta defense what ink is to the pen.

"When Joel is not in there, we are not in there," said the defensive coordinator, Jerry Glanville.

"I had worked so hard to get the attention of the league in 1980," said Williams, now fully recovered. "Not only that, but last year I was off to a quick start. In the first three games, I had a sack, a fumble recovery returned (57 yards) for a touchdown and an interception. Then I was sunk. Gone to oblivion."

Williams is a favorite in Atlanta, perhaps because he is of the same nature as the Grits Blitz linebackers. "In 1978, we blitzed and blitzed. We had fun," said Glanville. "We had (linebackers) Greg Brezina, Ralph Ortega and Robert Pennywell. Once, against Los Angeles, we blitzed on all but three plays."

"We knocked people down then. They didn't get off the line. That was the key to our defense in 1978," said Bennett.

Then came the rule changes that disallowed such ambushing tactics. The Falcons' entire defense suffered. Suddenly, 1978 and 1977--when the defense allowed an NFL record-low 129 points in Bennett's first season (7-7)--seemed distant in 1979.

"In 1979, everybody caught up with us; the fun was over," said Glanville.

"Last year, when Joel was hurt, he would go to the stadium 25 minutes early and work out before the team, testing his knee. Then, the team came into the locker room later and you could feel everyone watching to see if Joel would take off his pads or keep them on and play."

The Falcons are 2-1 in the preseason. After defeating Minnesota, 20-17, Atlanta lost to Baltimore, 34-3, in Arizona. Then, the Falcons beat Philadelphia, 24-21, here Saturday night.

The yo-yo continues.

"At least now, when we show up to games, we feel like we can win," said Bartkowski, entering his eighth season. "It didn't used to be like that."

Indeed, not. In the 11 seasons before Bennett arrived in 1977, the franchise was 50-100-4. Two winning seasons, no playoffs. Bad.

Said Bennett, 42-39 in five Falcon seasons, twice reaching the playoffs: "Tradition takes a while to build. In the 11 years before I got here, losing was the tradition."

The Falcons selected running back Gerald Riggs from Arizona State in the first round this year. "There were no defensive backs available," said Braatz.

Cornerback Bobby Butler, the 1981 rookie who could bench-press only a meager 190 pounds and who tired easily last year, is stronger (he is benching 260 pounds now).

Williams dropped the Eagles' Ron Jaworski on a punishing sack Friday night and forced him to throw quickly several other times. "Some of our players lost their jobs tonight," Philadelphia Coach Dick Vermeil said when someone boldly mentioned his offensive line.

Bartkowski is Bartkowski, and Jenkins and running back William Andrews (1,301 yards in 1981) no longer are holdouts. The Falcons' season-ticket sales were suspended at a club-record 57,500.

So, the Falcons enter the 1982 season possibly contenders, possibly prospects for another 7-9.

"Look at it this way," said LeBaron, "if the good-season, bad-season pattern holds, this should be our year."