SOME GROWING CONCERNS : The tallest and most talented youth basketball players are being expected to measure up to adult-like standards.

Alexander Lopez, 10 years old and six feet tall, is playing organized basketball for the first time. It shows.

A reserve on a team of the best grammar school players in the Valley, he runs up and down the court like a lost puppy--Alexander The Great Dane. His feet look like they’re trapped inside snow shoes. When the ball happens into his hands, it’s stolen more quickly than a wallet from a tourist on New York’s 42nd Street.

Yet listen to Nigel Miguel, an NBA rookie on the New Jersey Nets’ injured reserve list who is helping coach the youth team.

“Alex is going to be incredible once he gets the basic moves down,” Miguel said. “He will dominate whomever he plays against. Alex is the perfect project. He has something you can’t teach--size.”

Lopez’s grandfather, Bob Ledford, was a 6-7 All-American basketball player at Colorado State Teachers College in the 1940s. His father, Heriberto, is 6-5. His mother’s brothers are 6-10, 6-9 and 6-8. None played basketball but all are athletically inclined and sports-minded.

“Alex is projected by his physician to grow to about 7-0,” said Rich Goldberg, president of American Roundball Corp. Lopez, who is a fifth-grader at Mayall Elementary School in Sepulveda, plays on Goldberg’s sixth-grade ARC all-star team.

Deborah Ledford-Lopez, Alex’s mother, is less convinced that her son is destined for basketball stardom.

“Nigel and Rich seem to think Alexander has great potential,” she said. “We’ll see if he has the desire.”

Ledford-Lopez, a mathematics teacher, is torn between not pressuring Alexander and ensuring an opportunity for him to excel.

“He didn’t want to play but I signed him up anyway because he doesn’t see the whole picture,” Ledford-Lopez said. “Once he gets out there, he enjoys it. When he’s 15 or 16, I would accept no as an answer.

“I am careful not to push too hard. When I was a swimmer in high school, a girl I swam with was headed for the 1964 Olympics, according to her parents. They were super-competitive and pushy. She once told me, ‘If I don’t win, my mom will be so mad.’ ”

Such lessons are easily forgotten in the heat of a contest. After Alexander missed a shot during a recent game, his mother spoke sharply from the stands. “Get back on defense, Alex,” she said. “Get your hands up.”

Parenting a prodigy is clearly difficult.

But are high expectations unbearable for a boy who is off chasing lizards at a park an hour after pleasing adults on the court?

Bruce Ogilvie, a prominent sports psychologist and professor emeritus at San Jose State University, believes so. At clinics he holds for youth coaches, he tells them that physical and mental maturity do not develop at the same rate.

“Coaches and parents often see a child through his physical gifts, not realizing the inner clock determining emotional readiness,” Ogilvie said. “It is so easy when looking at potential to ignore a child’s innermost needs.”

Many professional basketball players are immature and cannot handle basic adult responsibilities, according to Ogilvie, who is a consultant to the U.S. Olympic figure skating team and the Golden State Warriors, Milwaukee Bucks and Portland Trail Blazers of the NBA.

He is currently counseling the Warriors’ Chris Washburn, a 6-11 center. A full-time “baby-sitter” has been hired by the Warriors to live with Washburn, who checked into a drug rehabilitation center in Van Nuys on Jan. 28.

“In my work I see NBA players who have great problems,” Ogilvie said. “People have been competing for their services as athletes since they were children. The sports experience retarded their social and emotional maturity.”

A budding basketball star, obviously, doesn’t always become a basket case.

Goldberg, who founded ARC in 1978, takes pride in the overall development of the boys he coaches. Perhaps Alexander Lopez is in good care, after all. Even the youngest boys are on a first-name basis with Goldberg. “I’m having fun playing for Rich,” Lopez said.

Ogilvie’s portrait of a troubled professional player does not fit Miguel, for instance, who improved from a bench-warmer as a junior at UCLA to a senior good enough to be selected in the third round of the 1985 NBA draft.

“He wasn’t the most naturally talented player, but he’s in the NBA because he works so hard.” said Goldberg of Miguel, who played ARC from the seventh through 12th grades and attended Notre Dame High in Sherman Oaks.

“And look, his spare time is spent teaching young players.”

Because he helps Goldberg, Miguel coaches the finest talent in the Southland. He talks about them as though they were called Magic and Dr. J, but Miguel’s Midgets will do as a nickname. The NBA is on hold until, oh, 1999.

“Cameron Murray’s ability speaks for itself,” Miguel said. “Duane Curtis may be the most complete player even though he’s the youngest. And Alex, that guy is going to be incredible.

“Now, JeCarl Riggins is wise beyond his years. And if Maje Kirchner doesn’t play well, we don’t win.”

Miguel’s assessment is restrained compared to Goldberg’s. “I’ll guarantee you these players will be excellent varsity players in a few years,” he said.

A guarantee from Goldberg, the grammar-school guru, may be good as gold. “Rich has a knack for spotting talent,” Miguel said.

Asked six years ago to prophesy on the promise of his prepubescent players, Goldberg might have said:

“I’ve got a seventh grader named Trevor Wilson who is a tremendous rebounder and works so hard on shooting that he’ll be a top scorer.

“The best sixth grader is a pure shooter named Steve Ward. And there ‘ s a fifth-grader in Simi Valley named Don MacLean who could turn out to be the best of all.”

Wilson was The Times’ Valley player of the year at Cleveland High last season and is now at UCLA. Ward is averaging 25 points a game for Calabasas High. MacLean, a 6-10 junior at Simi Valley High, is considered the best Southern Section player in the area.

Seven NBA players--Byron Scott, Stuart Gray, Darren Daye, Leon Wood, Forrest MacKenzie, Cliff Levingston and Miguel--and 38 players on major college teams played ARC while in high school.

“If Rich says a kid is going to be great, I’d take a look,” MacLean said.

The enthusiasm is understandable. There is nothing like untapped talent to titillate the senses. Is it dangerous to raise expectations high above the backboard?

“Youngsters are not emotionally ready for intense competition,” said Ogilvie of pre-high school athletes. “Coaches can’t believe it when I tell them kids aren’t thinking about professional or college careers.”

Said Eli Essa, an assistant coach at North Hollywood High who has coached youth basketball in the Valley for 12 years: “Projecting what a boy will become is a natural thing. It’s best to insulate him from the expectations and let enjoy every game for what it’s worth.”

But mention Robert Eugene Hill, a 13-year-old who Essa believes is the best youth player in the Valley, and caution is cast aside.

“I saw a story in Sports Illustrated about the best seventh grader in the nation,” Essa said. “I’d like to see him go against Robert. He could easily come off the bench for a varsity team. Right now.”

Cameron Murray is the Robert Eugene Hill of the fifth grade. He plays on sixth- and seventh- grade all-star teams and isn’t concerned by lofty goals. “I play because it’s fun,” Murray said. “I don’t think about high school and college much yet.”

He doesn’t have to because others are doing it for him.

Murray’s brother, Tracy, is one of the top scorers in the Southern Section, averaging 21.4 points per game as a sophomore at Glendora High. “Cameron’s going to be a whole lot better,” Goldberg said.

During a recent game, Cameron dribbled the length of the floor, passed off, took a return pass without breaking stride and laid in a left-handed shot off the glass.

“I was trying to draw a foul,” he said, with a generous smile.

Cameron Murray is unspoiled. Yet the list of dangers that can distort a youngster’s perspective is as long as a three-point shot: parental pressure, a prima donna syndrome, mad-dog coaches . . .

Witness a game three weeks ago. The coach of a team playing against ARC, a youthful man with a head full of prematurely white hair, lambasted a teen-age referee, screaming: “You aggravate the (bleep) out of me. What am I paying you for? Tell me your name or we’ll go outside and settle this physically.”

The exchange was within earshot of his team. One player tugged on the coach’s shirt, and the rest of the sixth-grade team glared as if to say: “Lighten up, coach.”

And every coach--when composed--has to listen to parents who believe special attention should be given to their talented child. Naturally, the player believes he deserves special attention.

“I look for that type of thing,” Goldberg said. “It’s easy to head off by conferring with the parents. These are all-star teams. They realize quickly that we stress mutual respect.”

Although they must share playing time, most ARC players don’t seem to mind being a spoke rather than the entire wheel.

JeCarl Riggins, a slick sixth-grade point guard, was replaced by Chad Dueker (brother of CSUN guard Troy Dueker) in a recent game. Rather than sulk, Riggins turned to Lopez, who also was entering the game, gestured and said: “Remember to keep your hands up at all times on defense, Alex. Use your long arms.”

Said Ed Corridori, coach of the ARC seventh-grade team: “On our team, there is none of the give and go. You know, ‘Give me the ball and go to hell.’ ”

Goldberg believes that UCLA Coach Walt Hazzard is benefiting from the team-first attitude instilled in Trevor Wilson, now a freshman forward for the Bruins who played six years of ARC.

“Walt Hazzard doesn’t have to worry about not starting Trevor,” Goldberg said. “All Trevor Wilson wants to do is win. He doesn’t mind coming off the bench.”

Besides teamwork, single-minded dedication to basketball is necessary to play on teams as demanding as those in ARC.

“These kids have a quality of dedication not often found,” Corridori said. “They are unspoiled and there is such a willingness to work on different aspects.”

David Bryce, coach of the eighth-grade team, is another proponent of a full calendar of full-court action.

“The strength of this program is that it is year-round,” he said. “It’s the only way for a player to grow.”

Or grow tired of basketball.

“Family, school and basketball,” Goldberg said. “That’s all they do.”

Beware of the narrowness built into such a regimen, Ogilvie warned.

“Under no circumstances cheat them out of childhood,” he said. “A coach’s primary responsibility is to allow the players to experience a child’s world.”

The day soon comes when players must give up other sports or give up year-round basketball. Ignacio Castro, a 5-9 12-year-old who Goldberg describes as “unstoppable inside,” is nearing a decision.

“I play baseball, too,” he said. “I’ll be the biggest kid in my little league. I like both sports.”

All youth sports are similar to the players. The only people who attend games share their last name. No cheerleaders jump and squeal to their exploits. It is an intimate, intense arena.

And it is a ready opportunity to instill more in youngsters than dreams of college or professional success. Precisely what is learned depends on the adults.

“The coach can contribute to the emotional growth and self-esteem of the players,” Ogilvie said. “If the coach is there solely for ego fulfillment, the players will suffer.”

An admitted jock, Ogilvie recalls with fondness being part of a championship football team at the age of 15. After conducting sports psychology research that has resulted in three books and 190 published articles, he believes a coach should have three goals for his players.

“The youngster should feel good about his body and realize he can enjoy what his body can do athletically,” he said. “He should learn social integration through failing and winning--learn behaviors that will carry him through a crisis later on.

“And a child should develop a sport ethic for the remainder of life. He should come to appreciate body fitness.”

That way, a boy like Alexander Lopez will be as well-rounded as he will be tall.