Despite such success stories as Baltimore's Carmelo Anthony, some critics say players who attend school for only a year can do as much harm as good. Prosser disagreed.
"As long as a young man is going to school, as long as he spends the year doing the right things, if he feels after a year he wants to do something different, I don't have a problem with that," he said.
Pro scouts also said they hope the rule pushes players to college. "You kind of hope that's what it does - that it would encourage them to go to school for a year and get another year under their belts of experience and growth as a basketball player and emotionally," said Dave Twardzik, director of player personnel for the Magic.
Longtime basketball recruiting analyst Bob Gibbons said the age minimum could benefit players who need to mature and college recruiters, who have lost potential targets to the pros in recent years.
"I don't think it's unfair," he said. "I think it will be important to the guys who just aren't ready and then for someone like LeBron, I don't think there are going to be any more LeBrons. I mean, even Dwight could have used a year in college to mature physically."
The rule will not keep pro scouts away from high schoolers, Gibbons predicted.
"They're still going to scout these guys, if for nothing else as a look to the future," he said.
That's among the reasons the age minimum will have little overall impact, some critics said.
"I don't think it will have much effect one way or another on the pro game, because there are so few 18-year-olds in the league," said Dan Rosenbaum, an economist at the University of North Carolina-Greensboro who studies NBA economics.
A look at this year's draft shows that only eight of 80 top prospects ranked by ESPN.com are 18, though eight of the top 19 picks last year would have been ineligible under the rule.
The rule will mainly affect shooting stars such as James, Rosenbaum said. "And I can't see how it's a good thing to keep a player like that out," he said.
Howard's behavior at the camp yesterday seemed a testament to the power of exceptions. Unprompted by anyone, he started pickup games with little kids and threw his arms around staffers he remembered from his years as a camper.
"He was actually, as a high schooler coming into the NBA, one of the most mature players in the NBA last year," McCormick said.
And on the court? Well, Howard remembered Garnett smacking his shot against the backboard and woofing, "I told you about trying to come into the league." But he said he went right back at his idol. When a camper asked Howard if he regretted entering the league at 18, he offered his simplest response of the day: "No."
Sun staff writers Jeff Zrebiec and Don Markus contributed to this article.