this past fall, Mastroeni pauses in the Rapids’ suite. On one side is the team’s boot room, where rows upon rows of cleats hang neatly. Down a hallway is his office and a lounge area where the walls are covered by whiteboards filled with schedules and formations and players’ names. To a novice, it probably looks like calculus; to a fan, it looks like a game plan for recovery.

Drew Moor has played for (here, in a 2011 match), against, and with Mastroeni.

In a trainer’s room, defender and team captain Drew Moor is rehabilitating a torn ACL. His injury and a few others wreaked havoc, forcing Mastroeni to pull players from different positions into the back line and search for someone to fill Moor’s leadership void in the locker room. (Moor is a 10-year MLS veteran and played on the 2010 MLS Cup team with Mastroeni.)Mastroeni is quick to take responsibility for the 2014 “cluster.” He says the Rapids’ roster would have benefitted from another veteran or two to provide leadership depth to his young squad. He also says his late arrival to the team meant he wasn’t able to implement as much mental training as his players would need. In short, he should have been able to do more. Mastroeni analyzes in an endless cycle of self-deprecation without ever appearing to be whiny or lacking confidence. He simply knows what he did poorly and what needs improvement.

He explains all this without pausing, as if he can’t be bothered to breathe. He often speaks like he played: measured but unrelenting. His nearly perfect sentences tumble out and over each other. Even when he corrects himself in the middle of a sentence, usually with the flicker of an eyelid, he does it precisely, as if he doesn’t want to disrupt the beauty of the phrase’s structure. It can be both exhausting and mesmerizing to listen to because each tirade contains so much information to unpack, digest, and implement. “It would have been easy for me as a first-year coach to place a lot of blame and make a lot of excuses throughout the course of this year,” he says. “The way I approached it is, ‘How can I use all this hardship to learn from it, to become a better coach, and to be the best coach I can possibly be?’ ”

As a young player, Mastroeni started keeping journals to log and evaluate his performance and motivate himself. Typical entries say things such as, You deserve to be on the field today, or, If you ever want to make it, you can’t go out to the clubs the night before and train like you did today. Now that he’s a coach, he’ll wake in the middle of the night to make notes on plays, tactics, and ideas about how to better communicate with his team. He’s obsessed with training’s mental aspect because it’s what made him successful. It came with a price: He often wound his mind so tightly during a match that he’d be too exhausted to speak afterward. His brain took just as long to recover as his body.

Although Mastroeni wants the same intensity from his players, he readily admits that the message didn’t translate into wins during his first year on the sideline. “I tell them, ‘For us to be amazing, to first be a good team, we have to all be thinking on the same lines,’ ” he says. “We’ll never have the Robbie Keanes of the world”—Keane is a veteran international superstar who’s finishing his career in Los Angeles, much like David Beckham did—“at our club. That’s just a truth of who we are as an organization. But we don’t necessarily need those players if, and only if, we can play as a unit. And playing as a unit means never tuning out for a single second during the game.”

That laser focus was his legacy as a player, so it’s natural that he’d carry it over to coaching. It’s what he thinks young American players need to embrace if U.S. soccer is ever to become a more dominant international force. “American kids, for the most part, have their social lives and then they have soccer as the sport they play,” Mastroeni says. “In the rest of the world, their social lives are a byproduct of soccer, the sport they play. That’s where the disconnect is.”

When Mastroeni was 15 years old in Argentina, practicing with a kid in sandals, he realized he’d need to do more than train hard. Plenty of athletes were as good as he was, or better. His advantage was playing smarter, being the best-trained brain on the field. If he can help young American players do that, to emulate what he did mentally on the pitch, the sport here could change. “We’re making strides,” Mastroeni says. “It’s impossible to change a culture overnight. It’ll probably be in the next 10 to 15 years.”

The Beautiful Game demands that a player gives so much mentally that the individual ceases to exist. Each player is but one part of 11 people moving the ball toward one goal and away from the other. There is no cessation. No time-out. No room for a mental lapse. Mastroeni has always given his mind to the game—and it almost cost him dearly.