In Houston, where hyperbole is the language, if not the law, of the land, football fans like to spout off geysers of superlatives about Oiler tailback Earl Campbell, their "gusher of a rusher."

Well, why not? It is difficult even for the tallest to lead the National Football League in rushing since Jim Brown in 1957, has meant to the Oilers, who for eight years before his arrival drilled nothing but dry wells at playoff time.

This season Houston finished 10-6, upset the Miami Dolphins, 17-9, in the American Football Conference wild-card game at the Orange Bowl Christmas Eve, and will play the New England Patriots Sundays at Foxboro, Mass., in the AFC semifinals.

Campbell, 23, justified being the first man selected in the 1978 college draft by amassing 1,450 yards rushing in 15 regular season games as an NFL freshmen, although he missed one game with a injury.

He shattered the rushing record for a rookie-1,162 yards, set by San Diego's Don Woods in the 14-game 1974 season-to become a shoo-in for rookie of the year and a likely candidates for player of the year.

The "Earl of Campbell" also ran for 13 touch-downs, including four in the single most electricfying performance of this NFL season. His 199-yard night was climaxed by an 18-yard sprint for the winning tochdown in Houston's 35-30 victory over Miami Nov. 30.

Campbell came out of the East Texas town of Tyler like a prairie cyclone, rushing for 4,444 yards at Texas and winning the Heisman Trophy as the outstanding college player in the country his senior year, when he gained 1,744 yards and scored 19 touchdowns.

He arrived at the Oiler training camp at San Angelo, Tex., last summer with five-year, $1.38 million contract and lucrative endorsements for products from snuff to ice cream.

With those credentials, and his rookie statistics, it would be easy for Campbell to have an ego and life style as grandiose as the raves accorded him by those admiring windbags in Houston, which is to say, larger than life. But the hyperbole of his hometown is not his style.

"I don't want to be a big shot," is his oft-repeated credo. "Maybe other guys do, but not me. The important thing is to be yourself."

Humility was an abiding lesson taught by his mother, who gave him solid roots and unshakable level-headedness.

Ann Campbell is a God-fearing, strong-willed matriarch who-against long odds after she was widowed when Earl was in the fifth grade-raised her close-knit brood of 11 children in her own image of basic human decency.

"The Campbell home was a weather-beaten shack between a peach orchard and an auto-salvage yard," noted Houston writer David Casstevens, who has visited there. "Ann Campbell somehow held the family together with hard work, a mother's love and the reassurance she found every Sunday at Hopewell Baptist Church No. 1."

If one asks the Oilers about Campbell, the portrait that emerges is not of a hotshot or showboat, but of a shy, taciturn and thoroughly unpetentious young perfectionist whose gravest fault is that he gets down on himself too easily

After his spectacular performance against the Dolpins in that rare suspense thriller among this season's succession of Monday Night Football bores, for example, he did not revel in his accomplishments.

Instead, he dwelled on a lone block he missed, allowing Miami to sack quarterback Dan Pastorini for a safety. "That spoiled the night for me," he said, even after atoning with the winning touchdown.

Campbell is quick to agree when Pastorini proclaims the Oiler offensive line the most underrated in the NFL.

"I'm not taking anything away from Earl, who's a great talent-the best guy I've ever seen carry a football," Pastorini said, "but somebody had to open those holes for him."

Campbell knows that. He thanks his klinemen-tackles Greg Sampson and Morris Towns, guards Conway Hayman and Ed Fisher, center Carl Mauck-after every game, and he took them all out to dinner after he broke the 1,000-yard barrier.

In vivid contrast to his bruising style on the field, Campbell's locker room demeanor is soft-spoken, head-down, withdrawn. He finds modesty becoming.

When he is not carrying the football, or blocking for a teammate who is, he becomes "Easy Earl"-the nickname branded on him in training camp by defensive end Jim Young because of the laid-back way Campbell saunters to the huddle after displaying his personal disco step: zip, zag, slither and bam.

Andy Borugeois, who coaches the Oiler offensive backs, once said of Campbell, "You know what he reminds me of? A Sunday morning. Just an easy Sunday morning."

But, oh my, those Sunday afternoons!

When Campbell runs with the ball, the team on defense holds its breath. Sometimes he just blows past people, leaving them untouched except by the turbulence he leaves in his wake. Other times he hurtles over, under, around or through bodies, leaving tangle of destruction behind.

He is a wonderfully versatile runner, both an explosive game-breaker and a reliable battering ram on critical short-yardage plays. At 5-11 and 224 pounds, he has speed, strength in his upper and lower body, and immense gifts for deception and acceleration.

Moreover, he can hit. "He's the toughest guy to tackle in the NFL%," Isiah Robertson said after being run over by Campbell on a fourth-down play early this season.

"I was right where I was supposed to be. I came up and, boom, boom, boom, he buried me," said the sincesuspended Los Angeles Ram linebacker.

Bum Phillips, the Oiler coach-general manager, gave Tampa Bay four high draft choices and promising tight end Jimmy Giles for the right to be the first to stick his thumb into the pie filled with college talent last May. Phillips was certain Campbell would turn out to be a plum.

Campbell's running style-hit the hole fast, break a big gainer when there is daylight there and grind out a couple of tough yards when there isn't-hasn't surprised Phillips. Campbell's jarring blocking and skill as a decoy have been pleasant bonuses that have made running mate Tim Wilson a more effective runner and receiver.

Campbell, in short, has brought balance to a Houston offense that used to specialize in plunging straight ahead until big yardage was needed, at which point Pastorini almost invariably threw to wide receiver Ken Burrough.

Wilson, a second-year man who was primarily a blocking back at Maryland, and a corps of good receivers and linemen already were there, but Campbell was the missing piece of the puzzle needed to establish a running attack.

Pastorini-with the options provided by Campbell, options the quarterback never had before-has been able to elevate himself from seven years of abject frustration and prove himself at the helm of a more-imaginative offense.

This was never more evident than Sunday, when the Dolphins keyed on Campbell, lest he burn them as he had five weeks before. They held him to 16 yards on 13 carries in the first half, but Pastorini went to play-action passes and completed 16 of 21 for 261 yards.

By thus forching the Dolphin defense to be more honest in the second half, he opened up the running game. Campbell had a subpar day as far as personal statistics are concerned, but he still wound up as the kleading rusher with 84 yards on 26 carries.

He also dived one yard for the game's final touchdown with 1:55 remaining to cap a 50-yard, 10-play march in which he had a crucial 20-yard sweep around right end.

"It was obvious that the Dolphins' objective was to stop Earl, but to do that you've got to give us something else," Pastorini said. "You can stop Campbell or stop our passing game, but you can't stop both."

"Pastorini used to be Dr. Bomb," but now he can hand off to Campbell, said Bob Matheson, an exasperated Dolphin linebacker. "That makes him a different quarterback.

"And when they put Campbell back there in the I-formation with two tight ends, he can go either way. That makes it impossible for the defense to cheat."

Phillips said he was not perplexed by Campbell's scant first-half yardage against Miami.

"He's the kind of guy you've go to give the ball to lots of times-25 to 30 times a game-no matter what he's doing," the coach said, echoing a theme he has preached since training camp.

"He wears a team down. Eventually he's going to break one. You can feel it, like a time bomb ticking. He keeps rocking, rocking, and all of a sudden, he's gone."

While Phillips was saying this, Campbell was a low-pressure area in the raucous, celebratory Oiler dressing room. His jubilation was tempered by puzzlement over the reasons for his meager 16 yards in the first half.

"Maybe it was a question of my running harder or looking for my holes better," he said quietly. "I wish I had some answers."

He didn't seem to appreciate what all the other Oilersdid. It was enough that he had given the Dolphins some questions. And that is no hyperbole.