Just ask Freddy Adu, a spindly 140-pounder when he turned pro. By his own admission, rather than sharpening skills and refining talents during training sessions with D.C. United, he often spent much of his time withstanding knocks and picking himself off the ground. Yet still a lot of American fans couldn't understand why he wasn't with the national team from almost day one while watching him dazzle the opposition at the U-17 and U-20 levels.
Height and weight aren't the primary determinants of progressing up the ladder of development, but size does matter. Smaller players need to be better in all other areas just to survive. What players often don't realize is that as they mature physically they also develop the psychological resilience to counteract whatever athletic gifts they may lack.
"Yeah, I do think some people thought I'd be with the national team all the time, but at the end of the day I fell in the same category with Bruce Arena as I was with almost every other coach in America, which was that I'm too small, and inexperienced," says Adu, who is in the squad for Sunday's World Cup qualifier against Barbados. "But I never really agreed with that. I never really did. I just kept working hard and I put on a lot of muscle weight, since that time, and I'm a thousand times better today than I was when I first came into the league."
Contrast his case with those of LeBron James, who rapidly adapted to the rigors of the NBA partially through his remarkable physique, and Jozy Altidore, the most expensive transfer in the history of American soccer who doesn't turn 19 until November, a milestone Adu reached this month.
"I've been working a lot with the weights but as you get older, things happen, your body changes," says Adu, whose increased power and strength after a season in the Portuguese league is quite evident. "That helped me get to the point I'm at right now.
"LeBron is blessed to be so big. I mean, he's big. When he came into the league, I thought, 'He's bigger than a lot of NBA players already.' He's got the physical tools, something I've never had my whole life.
"I've always been smaller than everybody else and that makes it a little harder for somebody like myself, but that's when you've got to use your brains more and work harder than anybody else."
Argentine sensation Lionel Messi is hardly a physical marvel, but training with Barcelona since age 13 has toughened and honed his body to the point that his sharp cuts, explosive acceleration, and amazing instincts limit the opportunities for bigger, heavier rivals to flatten him with a solid hit. Hopping between continents to play for club and country increases wear and tear on the body, so a strong physical foundation is essential.
"I put Jozy in the LeBron category because those guys are just physically, athletically, gifted," says Adu. "That is a very, very good starting point, especially when you have the amount of talent they have. It makes everything a lot easier."
MLS is less demanding, yet the same increases in suppleness and power and defensive commitment can be seen players like Sacha Kljestan, who, like Adu and Altidore, will probably be jumping between club ball and international duty with the Olympic and national teams this year.
Kljestan is just over six feet tall, and much stronger even if only slightly heavier than he was as a rookie in 2006.
"At the international level, you have to be ready to battle and fight and run for every ball," says Kljestan. "That requires physical and mental commitment that really drains you, no matter how big you are. But if you can't hold up physically, you're in trouble."
Says Chivas USA coach Preki, "He's a very good kid, a good listener and we're just trying to push him to the next level, because he does have all the tools if he wants to work a little more on the physical side of the game and the defensive side of his game."
Limited playing time with Benfica frustrated Adu in his first European season, but in the next few months he'll be called upon by his country to play in some incredibly important and competitive matches. Size may have hampered his progress in some ways yet surpassing physical obstacles helped forge him into a player capable of impressive displays like his first half against Spain in Santander.
Not everybody can be a Jozy, or a LeBron. The size of the heart, unlike that of the body, can only be measured on the playing field.
"You know what?" says Adu. "For guys like myself and I blame my mom for me being small, we've got to work harder, but that's fine. I'm going to work as hard as I need to, to get where I want to get to."