MARK EATON : This is a tall story that appears to have a happy ending. It’s about a late-bloomer who happens to be 7-5 and on his way to becoming an NBA star.

The moral of this story is that you can’t teach height.

That’s the premise upon which the National Basketball Assn., that shrine to the overactive pituitary gland, was founded.

The idea is to unearth someone who can swat down airplanes, put him in short pants and place the order for new letterheads--preferably something with world champion on it. King Kong was the prototype. But settle for anyone known as Human Eraser.

Introducing Mark Eaton. He stands 7 feet 5 inches, plays professional basketball for the Utah Jazz and is apparently on his way to becoming an NBA star. They don’t have a nickname for him yet, but there may be a contest soon.

If, however, there seems to you a certain inevitability to all this matching of height to professional success, think again. There’s a corollary to the rule, which says that height isn’t everything. Consult Goliath. Or Doug Flutie.

“I remember when he came into the league, he couldn’t walk and chew gum at the same time,” New York Knick forward James Bailey said of Eaton.

That Eaton could do them consecutively was the result of years of hard work. Height and agility, rarely companions, were constantly at odds in the case of young Mark Eaton. The only inevitability Eaton faced was a lifetime of hearing people ask him how the weather was up there.

“I’m not God’s gift to the game,” he once said.

In high school, Eaton’s best sport was water polo. He didn’t play varsity basketball until his senior year at Westminster High, where he sat on the end of the bench and suffered taunts from fellow students. He went off to school, but not to play basketball. Instead, he was studying auto mechanics in Glendale, Ariz. One day, while working at a Mark C. Bloome in Orange County, Eaton was sighted by an assistant basketball coach at Cypress College. The coach didn’t need a telescope.

After two years at Cypress, Eaton was in demand as an athlete and was even drafted by the Phoenix Suns, but his newfound popularity was not to last. He chose to play at UCLA, where he got lost, playing only 11 games his senior season and not many more minutes.

Still, the Jazz wasted a fourth-round draft pick on Eaton, figuring there were no other 7-footers left to pick from. Utah had finished last in the league in rebounding as well as blocked shots. Somebody tall might help.

“We had no idea that he would develop the way he has,” Utah Coach Frank Layden said.

Veteran Jazz center Billy Paultz, who at 6-11 is dwarfed by his teammate, said people shouldn’t be surprised that Eaton has progressed. “When you start from zero, that leaves some room for improvement,” he said.

Mark Eaton can’t get over it: Not only is he in the NBA, he’s a factor. Nobody drives down the lane when Eaton is in the way without thinking at least three times. As teammate Darrell Griffith said, “Nobody is going to jump over him.”

In his third season in the NBA, Eaton leads the league in blocked shots, averaging 5.6 a game, and is eighth in rebounding, averaging 11.1. He is second in the league in defensive rebounds. Although Eaton’s offense is still a few years away, Layden thinks Eaton ought to be an All-Star now.

One problem, he’s not on the ballot.

“They told me I was the last cut (from the All-Star ballot),” Eaton said. “I thought that was pretty good.”

You see, Eaton is still having trouble believing his press clippings. How can he suddenly be so good?

“Coming into the league, I just hoped to be a good backup center, come in for 10 or 15 minutes, pop around, play for a few teams and try to make a career of it,” Eaton said. “I felt if I got the shot that there were some things I could do. I didn’t know I could lead the league in blocked shots or be a top-10 rebounder.

“It’s a different feeling. I like going to a city, picking up a paper somewhere and seeing where the key to the game is going to be getting Mark Eaton out on the floor, making him play one-on-one defense. It’s satisfying to me, considering some of the players I have on my team--Adrian Dantley, Darrell Griffith--and they’re more concerned about me than they are about them. Set up on offense to stop me ? It’s hard to believe.”

It’s crazy but it’s true. He wasn’t good enough to play in high school or good enough to play at UCLA, but the Milwaukee Bucks recently designed their entire offense to take Eaton out of the game. The Bucks put their center near midcourt and just kept him there, making Eaton come out and guard him.

“You have to get him away from the basket,” Indiana Coach George Irvine said. “You can’t get him up in the air because he doesn’t jump. He just stands there and blocks your shot.”

The other night against Indiana, he smothered one, then caught the ball in the air, setting up a fast break. Eaton is very smooth with his blocks, tapping them to a teammate, never concerned with how a block looks. He doesn’t name them.

But he loves doing it, and the fans in Utah love watching him, this incredible hulk, moving easily along the baseline, clogging up the area around the basket. On Friday, they had a poster night featuring Eaton. It wasn’t original--Eaton for the defense--but it was the thought that counted. The thinking in Utah is that Eaton has played an important role in making the Jazz respectable.

Not only has he blocked more shots than any two players in the league, he is also becoming a fine rebounder. That part was work. Blocking shots is a matter of getting in the way. Rebounding demands some real agility. All that is missing is the offense. He still looks awkward, and his hook shot tends to hurtle down toward the basket.

Nothing came easily, of course. It took a great deal of work on Eaton’s part, and some faith on Layden’s.

“He has worked like no player I ever knew before,” Layden said. “I know a lot of pros who are willing to play in the summer league, but how many do you know who will work by themselves in the summer, just trying to improve?”

Eaton was the only one he could think of. He has worked on his agility, on his strength, on his hook shot. He has lowered his percentage of body fat from 18.6 to 8.5. He is staying out of foul trouble long enough to play 32 minutes a game.

Impressive even when sitting down, Eaton looks like anyone else, only larger. He’s very comfortable with his height, very personable and is happy to talk about his success story, one that took him from under a car in Orange County to the top of a hill in Salt Lake City, where he lives in a beautiful home 6,500 feet up and within casting distance of bass filled lakes.

He’s the only player on the Jazz who lives in Utah in the off-season. He stays there because it’s quiet and because he can work on basketball.

“I feel more agile, more comfortable on the floor,” Eaton said. “I still need to work on my offense. I should be able to average at least 10 points a game (He’s at 7.7 now, shooting only 42%). When the offense comes, I think I can be one of the best 10 centers in the league. And I think I’m getting close.”

It took him only half a season to become a starter in Utah. And only then did he begin to think what had happened to him before.

“Really, it’s the only time when I wanted to tell people, ‘I told you so,’ ” he said. “I’ve gotten beyond that now.”

Occasionally he allows himself to wonder how he couldn’t even start in high school. He does wonder how UCLA left him sitting on the bench. He wonders why it couldn’t have happened for him a lot sooner. But he doesn’t dwell on it, not when he’s having so much fun enjoying the good life now.

There were moments, however. One was his senior season in high school when he felt so bad about his playing that he all but dropped out of school, taking just enough courses to graduate. Even worse was his senior year at UCLA when he was left home from the last trip.

“If I ever felt cheated, that was the time I felt the worst,” he said. “I had worked so hard and it wasn’t like I was causing any problems. Coach (Larry) Farmer just told me he couldn’t use me that weekend. That really hurt.”

His confidence was never lower, but Eaton went to some tryout camps and then was drafted by the Jazz. Now, the story just keeps getting better.

“You’ve only seen the tip of the iceberg,” Paultz said. “He’s got a great body to play basketball. When he gets his offense down, nobody is going to be able to stop him. He’s already a force in the league and no one knows how good he’s going to get.”