D.C. United traded up to select Joe Willis 50th overall in the third round of the 2011 MLS SuperDraft. “We took a flier on him and I’m certainly glad we did,” said Coach Ben Olsen. (Ned Dishman/GETTY IMAGES)

More than four years had passed since D.C. United assistant coach Chad Ashton recruited a tall, gangly goalkeeper out of St. Louis to play for the University of Denver.

Ashton kept tabs on his former program after joining United’s staff, and especially on that lanky netminder. Joe Willis had grown into a 6-foot-5, 190-pound force in goal, earning all-conference honors three consecutive years. So during meetings in the fall of 2010, when United’s staff met to discuss potential college prospects, Ashton said he might have a steal.

“He goes, ‘Trust me on this one. This guy has a great demeanor. He’s 6-4, 6-5.’ He goes, ‘I think this guy is going to be special,’ ” D.C. United Coach Ben Olsen recalled. “We didn’t know him at all . . . and we took a flier on him, and I’m certainly glad we did.”

Since trading up to select Willis 50th overall in the third round of the 2011 MLS Superdraft, United has been overwhelmingly pleased by the 23-year-old’s development.

That growth has been most evident this season.

After stepping in as starter in a 3-1 loss to the L.A. Galaxy on March 18 when Bill Hamid left for U.S. Olympic qualifying duty, Willis has been impressive, allowing just one goal in his last two starts and making a strong case to remain in net even when Hamid returns from an ankle injury. He is expected to start Saturday evening when United hosts the Seattle Sounders.

“I think I’ve done well,” Willis said, downplaying the praise that’s been heaped on him. “I’ve done what’s expected of me, and the team is looking great.”

His play has not come as a surprise to those around the club, or to those who know Willis best. To them, it is the natural progression of a player who has maintained the same even-keeled demeanor and tireless work rate since he was a white-haired kid with a bowl cut on the fields in St. Louis.

“That’s Joe. He always works hard. He always has,” said his mother, Ann. “That’s why I’m so pleased for him. As a youngster all the way through, other friends would be doing things, but he would pass because he knew he had practice or other commitments with soccer. He’s always been committed to it.”

Willis was somewhat of a late bloomer. He played other sports growing up — baseball, basketball and volleyball — and on the soccer field moved full-time to goalkeeper only in his sophomore year of high school. As a prospect, Willis did not receive much interest from colleges until after a Christmas tournament in Florida his senior year of high school.

Ashton remembered the young goalkeeper then as not too different in some ways than the one he coaches now.

“He’s got a great personality,” Ashton said. “A great demeanor on the field, a really calming effect for his defenders.”

After his senior season at Denver, Willis spent some time overseas training with English clubs Tottenham Hotspur, Fulham and Cardiff City. He thought about trying out for the second-division USL before earning an invitation to the MLS combine and eventually being selected by United.

“He didn’t know if he was working for the number three spot, or number two spot, or what they had in mind for him,” Ann Willis said. “But he just wanted to go.”

Now in his second year, the qualities Ashton touted in that first scouting meeting have shined through. Willis also continued his physical transformation, adding muscle to his frame, and “you’ve seen the outcome this season,” United goalkeeper coach Pat Onstad said.

Willis looks the part now, a buzz cut and a mountain-man beard adding a rugged touch, and after operating for so long under the radar, he has finally worked his way out from “unknown” status.

“It’s been amazing how much I’ve grown,” Willis said. “And luckily I ended up here. The last year has been unbelievable.”