EL SEGUNDO, CALIF. -- It has not yet sunk into the psyche of Art Shell, or maybe he doesn't want it to -- yet. But no matter what happens against the Bills in Buffalo on Sunday in the AFC Championship he will have succeeded in turning the Los Angeles Raiders from a recent mediocrity to a black-and-silver success story.

The Raiders' coach hates talking about success right now, so close to the Super Bowl. "So close," he said. Talking about success right now is a kind of coaching taboo.

Under Shell, who replaced the fired Mike Shanahan on Oct. 3, 1989, the Raiders have become the Raiders again. They have one of the best running games in the NFL with Bo Jackson and Marcus Allen carrying for a combined 1,400-plus yards, they have an intimidating defense led by defensive end Greg Townsend, who has 15 1/2 sacks, and once again they are tough. And winning, baby, just winning.

Shell, at 44 the youngest head coach in the NFL, is 20-9 since owner Al Davis gave him control; 13-4 this season when they won their first AFC West championship, let alone their first playoff berth, since 1985. His record compares well to former Raiders coaches after 29 games. In fact John Madden (20-6-3 after 29 games), John Rauch (22-6-1), Davis (16-11-2) and Tom Flores (18-11) didn't win as many games in their first full season as head coach as Shell has. The team is 14-2 at the Los Angeles Coliseum under Shell, which is understandable since he preaches that true Raiders don't lose at home. Shell played on Raiders teams that won 80 percent of their home games.

He was the left tackle for the Raiders from 1968 until he retired in 1982. He was voted to the Pro Bowl eight times -- the most of any Raider -- and elected to the Hall of Fame in 1989. Nicknamed "Goliath" in his playing days because of his solid 300-pound frame, Shell was an assistant with the Raiders from his retirement until Davis selected him as coach.

Shell is one of a kind in the NFL, the only current black head coach and only the second ever. Fritz Pollard, who was player-coach of the Hammond (Ind.) Pros during 1923-25, broke the color line before it was more firmly drawn.

Shell doesn't like to talk about himself as The Black Man As Head Coach. Shortly after he was named to the position, civil rights leader Jesse Jackson phoned to congratulate him. But Shell didn't mention the phone call for days, and then only after being asked about it did he discuss it. He was more overwhelmed when his oldest son, Art Jr., told him how proud he was that his dad helped break the color barrier for NFL coaches.

While he realizes its social significance, he played down any racial aspect and emphasizes what he says really counts, that he must be a Black Man As Head Coach Who Wins.

"It is a historic event and I understand the significance of it," said Shell, who had been a third-round draft pick out of University of Maryland-Eastern Shore (at that time Maryland State). "But the main thing is, I know who I am and I'm proud of it. . . .

"I have confidence in my ability as a coach. I have a lot of confidence in my ability to deal with the players on this team and to deal with this organization. So if something comes up, I stay on the track I have designed for myself and I don't get off of it. I won't let undue pressure come from outside and force me to change my mind about anything." Where He's Coming From

Shell should be proud that he has taken basically the same body of talent his predecessor had, and has transformed them from losers to winners. The reasons Shell has been able to do that in such a short time vary, but one is quite clear: His status as one of the best offensive linemen ever has helped him gain the utmost respect from his players.

"You're basically playing for someone that's one of the guys, one of the boys," said nose tackle Bob Golic. "It's easy to play for him and do things his way because everybody knows that when he played he was the type of player everybody respected. He was the guy that loved the game, the guy that went out there and played under any condition. Healthy, injured, no matter what, he loved playing the game.

"His competitive nature was always pretty evident. And you can see that in the way he coaches; it still exists. Knowing that he was a player, knowing that he knows the mentality of the player . . . it makes it easier for players to respond to his guidance."

It was as a player that Shell began to craft his personality. He is a tough man, but not a screamer like so many head coaches. Rather, he is glacier cool, his dissatisfaction evinced in the form of a look or stare; the way he moves his eyes or shifts his weight. He must have the best coaching look on the sideline of anyone in the NFL.

"We know him well enough," Golic said, "the little subtleties or change in his face and in his voice when things are not going well. His voice drops even lower. Pretty soon you're going, 'What?' But I mean you can see it.

"Sometimes it's so subtle: Just a look, just a glance, just the way he carries himself. All of a sudden it's like, 'Okay, we better stop messing around. Let's get serious.' It's amazing how everybody can pick that up."

In Oakland and, in his final year, Los Angeles, Shell was part of a team called "left-handed" because the Raiders usually then ran left behind Shell, center Dave Dalby, left guard Gene Upshaw and tight end Dave Casper.

Shell's toughness was well documented in his playing days. He once tore ligaments in his left knee, an injury that at the time ordinarily would have ended a player's season, but Shell missed just five games. 'I Was Able to Focus'

At 6 feet 5, he was an excellent and imposing pass blocker and perhaps had his best game in Super Bowl XI as the Raiders rushed for 266 yards. Shell went against Minnesota Vikings lineman Jim Marshall, who had no sacks, tackles or assists in the game.

"Art would kill you with kindness," former Denver Broncos and Raiders defensive lineman Lyle Alzado once said. "The first time we played, he smiled and said, 'How you doing, Lyle?' I thought, 'What the hell is this?'

"He proceeded to drive me off the ground, drop me on my back and run over me. Art was impossible to rattle. I'd talk about his mother, his sister and brothers. He ignored me. I hated Art Shell."

"I was able to focus on just playing football," Shell said. "Nothing else. I try to instill that quality in my players."

His coaching style is totally opposite that of Shanahan, a strict disciplinarian who never fit into the Raiders' way of doing things. Shanahan had hoped to instill discipline in a wild and carefree bunch, but the strategy backfired with a series of silly rules: no eating sunflower seeds in the locker room; everyone finds a seat at team meetings; and, most exasperating of all, no sitting on helmets at practice.

That's the kind of stuff high school coaches do. But the Raiders?

"We had assigned seats in meetings," defensive lineman Howie Long said. "I didn't do well with assigned seating in high school and I didn't do too well with it here."

Shell has only two rules: Be on time and concentrate.

"He treats you like a man," Long said. "He doesn't bog you down with silly rules."

Said offensive lineman Max Montoya: "The thing about Art is that he talks with you. He comes up to you before a game or practice and just talks. We talk about football or anything else."

Now Shell is one victory away from the Super Bowl. In typical Shell fashion he deflects any credit from himself to his players.

"They are the ones playing great right now," he said. "They're the ones playing the game, not me."

But as Allen, who in his rookie year ran behind the blocks of Shell, said, "We are a reflection of Art."

The Raiders, Allen added, are back.