There were times last Sunday when Miami defensive back Mike Kozlowski looked into the backfield of the San Diego Chargers, focusing specifically on quarterback Dan Fouts. He was delighted with what he saw.

"You should have seen his face," Kozlowski said the other day. "It was like panic. You could tell he was feeling the heat, and he just wanted out of there. You could see him look downfield where his receivers were supposed to be, and they'd have three of us around 'em, and he'd have to look somewhere else.

"Except there was nowhere else."

It is the sort of look, that look of panic, that Miami defenders are hoping to see in the eyes of New York quarterback Richard Todd Sunday when they play the Jets in the Orange Bowl for the AFC championship.

Most of the Dolphins know they have come this far in large part because of their defense. That defense has yielded 256 yards a game total offense, 114 yards passing, both figures the best in the NFL.

And many of the Dolphins' defenders find it somewhat amusing that they are now being praised from Key Biscayne to Key West. "A lot of people got down on us last year, but we didn't have all the problems they thought we had," said safety Glenn Blackwood, who had two interceptions in Miami's 34-13 victory over the Chargers.

"There was a stretch of games in the middle of last season when we gave up a lot of yards about four or five straight weeks. What people forget is we played pretty good defense our last four games of the season. It's carried over, and we get better every week."

A year ago, the Dolphins' defense had serious problems. Starting cornerback Don McNeal (hamstring) and defensive end Doug Betters (staph infection) had limited playing time. Free safety Lyle Blackwood, Glenn's brother, didn't become a starter until the seventh game. Kim Bokamper had switched from linebacker to defensive end during training camp. A.J. Duhe was in his second year as a linebacker after switching from the defensive line, and linebacker Bob Brudzinski was still learning the system after being obtained in a trade with the Rams.

And learning the system under assistant Bill Arnsparger--"the best football mind in the game today; a genius with defense," Kozlowski says--has never been a particularly easy task.

"In the past, it's always been him trying to convey his thoughts to us," Kozlowski said. "Now, I finally know what he's talking about; before, he used to get a lot of blank stares. His calls are brilliant. He's got a coverage for any situation. He's usually way ahead of anything anybody throws at us."

Arnsparger has been with Don Shula in Miami for 10 years, sandwiched around 2 1/2 years as head coach of the New York Giants. He received a game ball after the 1973 Dolphins won a second straight Super Bowl, but he is a man who does his best work in dark film rooms, not the spotlight of national attention.

"We don't do anything nobody else does," he insisted. "There are no secrets to defense. Everybody has the same combinations, the same coverages. Everybody knows everybody else. We've just been playing real well together."

Clearly, there is more to it than that. Opposing offenses never really know where the next Dolphin is coming from. Kozlowski, the nickel defensive back, frequently blitzes from what appears to be a linebacker position. Bokamper occasionally abandons his defensive end spot and makes like a linebacker in pass coverages, just like the old days.

Meanwhile, the defensive backs are frequently shifting back and forth from man-to-man to zone coverages, occasionally blitzing from the safety positions and constantly trying to jam receivers at the line, throwing them off stride and out of their usual patterns.

"The key to it is that it always looks the same; that's what I mean about disguising our defenses," Kozlowski said. "I can be in the same position on two different plays and be covering two different people. The whole idea is to create confusion, to give the pass rush that extra second that could lead to a sack or make the quarterback hurry his throw, just like we did against Fouts."

Can the Dolphins accomplish the same sort of havoc against the Jets on Sunday?

"I know Richard Todd never has a look of panic," Kozlowski said. "I know him. A lot of us know him. He's a great guy and a quality quarterback. He doesn't panic, he gets mad. And when he gets mad, he plays better."

The Dolphins also know the Jets are not as pass-oriented as the Chargers. They know they cannot concentrate on pass defense with Freeman McNeil slashing out of the backfield, and they know they cannot concentrate on McNeil for fear of getting burned by the Jets' afterburners--Lam Jones and Wesley Walker, the fastest receiver combination in the NFL.

"And Todd will do more things (than Fouts)," Shula said. "He'll throw some dropback, but he'll also give you a lot of movement. He does a lot of bootlegs. He faked the inside handoff and kept it the other day (in the Jets' 17-14 victory last week against the Raiders). Did you people notice that one? We did. They do more things than just drop back and throw the football like the Chargers do."

But then, so will the Dolphins do more things to stop a Jets offense that was third in the AFC, averaging 357 yards a game. "We've got to play our coverages better and not let them get anything cheap or quick on us," Arnsparger said. "They can score from any place on the field."

"We know what we have to do," Kozlowski said. "Our defense is playing with great confidence right now. We thought we could shut out San Diego, not just shut 'em down. We feel like that every week. We're doing nothing different; we're just doing it right."