KANSAS CITY, KAN. – After his first game captaining Minnesota United, Michael Boxall heaved a big sigh and took several seconds to pause before answering how he assessed the Loons' 4-1 loss at Sporting Kansas City.

"The performance was nowhere near good enough," was what he eventually said.

The Loons are still winless at Children's Mercy Park after Sunday's loss to their rival in front of an announced crowd of 20,442. With the three points, Kansas City regained first place in the Western Conference, which it briefly lost Saturday night to FC Dallas, and improved to 8-2-4. United, at 5-8-1, sits in ninth in the West.

Coach Adrian Heath again lamented poor play away from home and his squad's general lack of depth that the club still needs to work on in this second season.

"There's no way of dressing it up: We're very brittle on the road," Heath said. "And we're conceding too many goals to try to win games."

Heath said his squad doesn't have the mental toughness to succeed away from TCF Bank Stadium. Whenever Kansas City put pressure on, the Loons looked ready to fold. And that happened often: Kansas City ended the game with almost 69 percent possession.

For the 10th time in 14 games this season, the Loons gave up the first goal. After right back Tyrone Mears and midfielders Ibson and Rasmus Schuler couldn't clear the ball, Kansas City's Yohan Croizet intercepted the ball and fed Daniel Salloi, who beat United goalkeeper Bobby Shuttleworth in the ninth minute.

The Loons, though, rallied three minutes later when Mears, whom Kansas City failed to close down, smacked a distance shot past Kansas City goalkeeper Tim Melia. It was the defender's third goal in four MLS seasons.

After the equalizer, United gained some momentum. But the team broke down toward the end of the half, and it proved costly. Kansas City midfielder Wan Kuzain, who was an early sub after an injury, hit a one-timer that deflected slightly off United center back Michael Boxall and into the goal in the 35th minute. Then two minutes later, Shuttleworth couldn't hold on to a shot from Kansas City midfielder Cristian Lobato, and the ball trickled over the line before Boxall could clear it.

Heath tried to patch the holes at halftime, subbing on midfielder Maximiano and taking off winger Alexi Gomez, who was struggling against Kansas City's Graham Zusi on the left. That move eventually backfired; Maximiano earned two yellow cards in 20 minutes and put United down to 10 men with 25 minutes still to play.

Diego Rubio scored one more for Kansas City before the final whistle sounded.

Despite the result, Heath said he felt better about how his team fared in Kansas City this year compared to last, when the Loons lost two games by a combined 7-0 and put in the worst effort Heath said he had experienced as a manager in Minnesota.

But Boxall wasn't with the team for those games, so this loss wasn't easy for him to take.

"I just feel so bad for our fans who traveled all this way and saw that," Boxall said. "It just feels disgusting right now. Most definitely the result, but just the performance here … we sold ourselves way short of where we should be."

Sporting Kansas City midfielder Yohan Croizet, left, and Minnesota United midfielder Rasmus Schuller struggled for the ball during the first half of an MLS soccer match in Kansas City, Kan., on Sunday. Sporting Kansas City won 4-1. (Brian Wicker — Associated Press/The Minnesota Star Tribune)

Loons midfielder Miguel Ibarra, right, fended off Sporting Kansas City midfielder Roger Espinoza during Sunday’s loss. The Loons fell to 5-8-1 while league-leading KC is 8-2-4. (The Minnesota Star Tribune)