The U.S. is the birthplace of countless international athletic legends, from swimming's Michael Phelps to tennis' Venus and Serena Williams. But Uncle Sam has repeatedly failed to produce a superstar in one sport: Soccer. The U.S. team's uneven performance at the Gold Cup regional championships — after lackluster early games, it trounced Jamaica on Sunday to secure a spot in the semifinals — has commentators questioning America's inability to nurture a true soccer great. We have a big population, a wealth of resources, and nearly 15 million youngsters kicking the ball around. Charlie Stillitano, a former Major League Soccer executive, calls the lack of a superstar "befuddling." Here, five theories behind the shortage:

1. American kids have too many choices
Many young American kids start out playing soccer, but then abandon it for another athletic option — football, baseball, basketball, track and field, and more — when they hit age 9 or 10, says Sean Dowling at Bleacher Report. In most countries, kids don't have as many choices, and the best athletes stay on the soccer field.

2. Would-be American stars abandon us
Giuseppe Rossi and Neven Subotic — "two huge names" — have left the United States Mens National Team in recent years and gone on to have "superb careers" elsewhere, says Dowling. Rossi was born in New Jersey, but chose to play for his parents' native Italy, while Subotic came up through the U.S. youth ranks before deciding to play for his native Serbia. If they'd kept playing in the States instead, they could have been heroes, and "had a massive impact on our national team success and popularity of the game for many years to come."

3. The U.S. lacks superb coaches
Great American players don't have access to great instruction, says Eric Wynalda, a former U.S. national team player and a U.S. Soccer Hall of Famer, as quoted by The Wall Street Journal. "The talents and abilities of our players now exceed the knowledge of the coaching, so the result is stagnation."

4. We don't make soccer a priority
"We just don't have the infrastructure" to properly foster top young talent, says Ben Alamar, the founding editor of the Journal of Quantitative Analysis in Sports, as quoted by The Wall Street Journal. "Who would a potential U.S. superstar even play against here to get to the point where they can be at a high level in Europe?" The only problem with that theory, says Matthew Futterman in the WSJ, is that countries with far fewer resources, from Cameroon to Cote d'Ivorie to Trinidad, have managed to produce superstars.

5. We'll get there... one day
Let's not harp on the Gold Cup mishaps, say Luke Cyphers and Doug McIntyre at ESPN Soccer. Even the world's most storied national teams often disappoint at the beginning of big tournaments. And it's hardly shocking that the U.S. hasn't produced its own David Beckham yet, says Sunil Gulati, the president of the U.S. Soccer Federation, as quoted by The Wall Street Journal. "There are so few players at that level. But fear not. The U.S. is bound to get there one day."