The children didn't even have to call his name. Rickey Henderson knew they wanted him to leave batting practice and come over to the box seat railing and give them a thrill.

The huge majority of professional players, despite their vast salaries, never hear the high-pitched voices imploring them to squander two minutes of their precious time. Henderson, born in Chicago and playing in Oakland, had time for the kids of Baltimore, although there was nothing in it for him but their delight.

After the autographs and the small talk, the 24-year-old Henderson, who stole an almost-unthinkable, all-time record of 130 stolen bases last season, searched the batting cage, the dugout and the tunnel until he found an old broken bat.

"Pick a number from one to 10," he said to three boys whose eyes were falling out of their heads at the chance to get a big-league bat to repair.

Henderson, who has been on a thieving tear lately, stealing 16 bases in nine games (including 10 in one three-game stretch), decided that "seven" was the winner. Somewhere, a boy will always wonder whether he had the right number or the right smile.

As Henderson jogged to the outfield, he spotted another cracked bat by home plate, reversed his field and brought it back to the disbelieving youths. This time, no numbers were picked. He had spotted a tiny blond girl in a pink dress who had been shoved to the back by the boys. He parted their sea of hands and gave the girl a souvenir.

"I love kids. I remember when I came to the ball park, it made my days if one of the players gave us a minute. I want to satisfy their joy," he said.

Henderson is going to be spreading joy for many years. What Willie Mays, and few others, have brought to baseball, Henderson has--a child's enthusiasm and an ambassador's touch. "I want to play this game a long time . . . 15-20 years."

That's why 1983 has been such a pleasant development for those Henderson watchers who hope that the A's left fielder will fulfill every iota of a potential so large that, in time, he may go down as the game's greatest leadoff man. This is the year that Henderson has achieved a sensible cruising speed.

In his first four seasons, Henderson proved that he was a dazzling talent, a flashy stylist, a man who could make 50,000 eyes focus on him alone. Now, he is proving that he can find a style and pace of play that will allow him to stay in one piece and be a star for the rest of the century.

This is a man who has 3,000 hits and 1,500 walks in his future, as well as a career stolen base total that should obliterate Lou Brock's mark of 938. Henderson already has 367 and he's barely a baseball child.

Typical of the excitement Henderson causes was his performance tonight against the Orioles. He had three hits--including a long home run--a stolen base and a leaping catch that robbed an Oriole of a double.

Oddly, this has been a season when many fans mistakenly thought Henderson was in a slump, suffering, perhaps, from the aftereffects of his grinding pursuit of Brock's steal record of 118 last year. Actually, the Henderson of 1983--who has 48 steals in 58 attempts through 85 A's games--has been just as productive as the Henderson of 1982.

Last year, Henderson batted .267, led the league in walks and had a .399 on-base percentage. This year, Henderson is hitting .273, leading the league in walks (55) and has an on-base percentage of .401.

More important, "I've learned out how not to get picked off first so often," said Henderson, who was trapped off base 14 times last season, 12 by lefties, compared with three pickoffs this season. "Now, I'm picking up keys more and not guessing."

Last season, Henderson was thrown out 42 times and his theft percentage was .756. This year, Henderson is running at a 90-steal pace, but his percentage is .828. To baseball insiders, that's an even greater improvement than it seems.

Many managers and serious baseball statisticians think that being picked off or caught stealing is so damaging that it requires two successful steals to balance the ledger and make the gain worth the risk. By that standard, 84 of Henderson's steals last year were an atonement for his 42 extra outs. Therefore, his 46 other steals were his "plus."

By this stringent measurement, Henderson is already plus 28 for 1983 and is having, by far, his most efficient stealing season from a team point of view.

"Rickey's role is different this year. Last season, the team was going nowhere and his record chase brought excitement to the team," said first-year Manager Steve Boros. "I think he realizes that he needs to be more selective, more efficient with his steals to be the player everyone knows he can be.

"He's a very proud individual and there are other goals he wants to reach and can reach--hitting .300, winning a batting title someday, hitting with more power and being a great left fielder with a strong arm," added Boros. "If he's always banging up his body trying to steal 130 bases, there's not going to be enough left of him to do those other things."

Also, Boros and A's co-owner Wally Haas say that, in a few years, when the A's hope to have built a contender, they want Henderson to be in his prime, not be in a sling.

Too many players have been embittered by record chases. Henderson said, "It was like what I thought it would be. I enjoyed it. I'm an up-and-coming guy in the game who's going to be around for a long time and people got to know who I was.

"Lou Brock was a great man. He was really gracious," said Henderson. "He told me years before that I was going to do it . . . I was really happy to get the record because people will remember you as long as the game is played. That's a joy."

In Henderson's case, the joy you take really is equal to the joy you make.