Minnesota United center back Michael Boxall thinks there might be a conspiracy afoot.

Opponents have shut out the Loons in three of their past four games, including Friday’s 1-0 loss to FC Dallas. Before this game, one too many passes seemed to be the problem. Against Dallas, the ball always seemed to sail a foot off target.

“We really need to check the size of the goals at the training ground,” Boxall said. “Make sure they’re not bigger than regulation size.”

Those near-misses marred the result at TCF Bank Stadium in front of an announced crowd of 22,345. Now halfway through the MLS season, the Loons are in ninth place in the Western Conference at 5-10-1, six points out of playoff contention. Dallas tied Sporting Kansas City for points atop the West at 9-2-5.

United had to deviate from its usual formation with a 3-5-2 setup, as winger Miguel Ibarra was not available for the game after a red card suspension. And it worked fairly well. The game was pretty even, with Dallas seeming to have the edge on possession in the first half while the Loons had more scoring chances.

Dallas was able to capitalize on its chances, though, as midfielder Santiago Mosquera sent in a corner kick in the 59th minute that forward Roland Lamah rose to meet and head past United goalkeeper Bobby Shuttleworth for the only score of the game.

Heath said the goal allowed was almost like déjà vu, as the Loons have left unmarked opponents free to score on corner kicks on several recent occasions. But he said the Loons’ 15 shots and 13 corners might be the team’s most in the MLS era, and that’s encouraging progress.

“There’s a lot of disappointed men in that dressing room,” Heath said. “They’ve done enough tonight to take something out of the game, and they know that. But football sometimes doesn’t give you what you deserve.”

Calvo an All-Star

Fresh off playing in the World Cup with Costa Rica, Francisco Calvo will be Minnesota United’s first representative in the MLS All-Star Game on Aug. 1 in Atlanta.

The Loons captain is one of 14 selections from All-Star and Atlanta United coach Gerardo “Tata” Martino the league announced Friday. There are 26 players total, including fan-voted players and commissioner’s picks.

“It’s good for him,” Heath said. “Great exposure for the club.”

While Calvo drew scrutiny after a rocky start to the season with several individual mistakes costing United goals, Heath has maintained he could become one of the league’s best center backs.

Calvo, 25, started Costa Rica’s first game, a 1-0 loss to Serbia, and came on as a substitute in the second, a 2-0 loss to Brazil, before sitting out Costa Rica’s 2-2 draw against Switzerland.

He returns to the Loons on Sunday. Heath said he will assess whether Calvo is ready to play against Toronto FC on Wednesday night at TCF Bank Stadium.

• Midfielder Rasmus Schuller came off in the 77th minute as a precaution for thigh tightness.