This time of year, I am disturbed at the number of curveballs we see being thrown during the Little League World Series.

I coached youth baseball for eight years, each spring and fall. Three years ago, I wrote that Little League Baseball should ban the use of the curveball by its young pitchers.

The evidence seemed clear -- and sports injury doctors seemed to all agree -- that pitchers who were 13 and younger were not physically capable of handling the torque and strain on the elbow when throwing a curveball. The ulnar collateral ligaments connecting the lower and upper part of an arm simply couldn't survive the strain, they said.

Now, there is evidence the curveball may not be entirely to blame. But there is still debate over whether it should be allowed at such a young age.

Little League and others did separate studies -- and got somewhat similar results showing that injuries can result not just from throwing curveballs, but from kids throwing too much, with too little rest between pitching appearances.

Little League instituted strict pitch-count and innings-pitched rules five years ago. But those rules don't apply to non-Little League-sanctioned games.

"The difference now is, kids are playing on a number of travel and showcase teams outside Little League, and they have no such rules," says Lance Auken, vice president of communications for Little League Baseball.

"Travel ball has no rules on pitch count or number of innings pitched. So you now have kids throwing 300 to 400 pitches over a four-day period," he says.

Doctor: 'Don't throw curveballs until you can shave'

Little League Baseball commissioned its study with USA Baseball and the University of North Carolina. More than 1,300 pitchers of all ages were examined. For the Little League age group, 409 pitchers were analyzed, looking for which factors influenced injury risk.

"What was causing arm problems was not the curve ball, but the overuse of the arm. It found no evidence to say breaking pitches caused no more injuries than any others," says Auken.

Meanwhile, a group of doctors including Dr. James Andrews, the country's leading doctor in sports arm surgeries, conducted their own study. Andrews specializes in "Tommy John" surgery, which reconstructs the ulnar collateral ligament and is named after a former Major League pitcher.

Andrews and his team at the American Sports Medicine Institute did their study in a laboratory, not on a field. And they found throwing a curveball enacts no more force on the arm than a fastball.

But, they say, throwing curveballs early can lead you down a dangerous path later in a baseball career.

"Dr. Andrews still insists, 'Don't throw curveballs until you can shave," Lanier Johnson, Executive Director of ASMI told CNN.

And, he acknowledges, "That was a controlled lab setting. The field of play during a game isn't like that."

"We've tracked Little League games right through the Little League World Series, and as the competition grows, the kids throw curveballs up to 70% of the time," Glenn Fleisig, ASMI's director of research and co-author of the Andrews study, told ESPN The Magazine.

"It's good that Little Leagues have enacted rules on pitch counts, but for say, a kid in the Dominican (Republic), if you see an unusually developed curveball at an early age, who knows the mileage on that arm?"

Johnson says, "The kid who throws all those curve balls in the Little League World Series is a hero. But does he ever get a change to earn a college scholarship or sign a major league contract? Do you want to take a chance on your son or daughter to get a college scholarship? Do you want to be a hero at 13 or 14 but never much else after that?"

Surgery on the rise for young players?

Even though Little League has instituted new pitch count rules, ASMI says Andrews has performed about seven times the number of arm operations on young pitchers that he did 15 years ago.

So why not err on the side of caution and take Andrews' advice?

"(Andrews) himself will say that is an opinion of his, and is not based on any empirical data," Auken says. "There wasn't any evidence in this study. It's a fine distinction between the two."

"Little League has always been the leader in sports safety. We make changes in our sport based on data, not on feelings. We act out of scientific evidence," he says.

However, Andrews' office does agree that kids who pitched while fatigued are 36 times more likely to have serious arm problems.