– Righthander Ervin Santana appeared to be outdueled by Royals lefthander Danny Duffy on Sunday, but manager Paul Molitor’s mood after the game suggested that the Twins’ 2-1 loss to the Royals was based on other factors.

Molitor knew that his team bungled another one, as Kansas City swept a four-game series with the Twins at Kauffman Stadium for the first time since 1975. It wasn’t about Santana getting beat, it was about them wasting Santana’s seven innings of two-run ball.

And falling to 0-7 at Kansas City this season.

And falling to 2-11 against the Royals overall.

There definitely was an edge in Molitor’s voice after loss No. 76 on the season.

“We hung in there today with Ervin’s help,” Molitor said, “but it’s some of these situations and environments where guys need to step up and our mental toughness needs to improve, and hopefully we do that as we get more experience for our younger core. That’s that what it takes to win on the road, especially against a team that is playing well.”

Kansas City has won eight consecutive games, the Royals’ longest streak since August 2014. Five of those victories have come against the Twins.

The Twins’ inefficient offense has to take some of the blame. The Twins loaded the bases with no outs in the second inning against Duffy and had a chance to get some licks in on one of the hottest pitchers in the league.

But Eddie Rosario struck out, Kurt Suzuki flied out and Danny Santana hit into a fielder’s choice to end the inning. The Twins also had a runner at third with one out in the fourth, but he was stranded as well.

“When you have your best pitcher going,” Molitor said, “those things can become huge.”

The critical miscue came on a play that was scored a hit. With the score tied 1-1 in the bottom of the sixth, Lorenzo Cain was jammed with a pitch and had trouble getting out of the batter’s box when he hit a grounder to short that bounced off Twins shortstop Jorge Polanco’s glove. Cain reached first, and it was inexplicably ruled a hit.

“I think that’s an error,” Molitor said. “It’s a tough play, but it is a major league play.”

Polanco wasn’t sure if he had a chance to throw Cain out. “But if I catch the ball, I’m going to make the throw,” Polanco said.

On cue, Eric Hosmer bashed a double to center, scoring Cain to give the Royals a 2-1 lead.

Duffy (11-1) went 6 ⅔ innings, giving up one earned run on eight hits and two walks with four strikeouts. He has won 10 consecutive decisions. Kelvin Herrera pitched a 1-2-3 ninth to earn his seventh save.

Santana (6-10) held the Royals to two runs over seven innings on five hits and one walk with 10 strikeouts, his most strikeouts since Sept. 5 last year at Houston. He has held opponents to two or fewer earned runs in 10 of his past 11 starts, going 5-2 with a 1.91 ERA in those games.

It capped a series in which the Twins were blown out in two games and lost by one run in the other two, including Friday when the game was delayed by rain and power outages and ended past 2 a.m. Saturday.

The common denominator this series: The Twins’ failure to execute. And it’s killing Molitor.

“I’m very frustrated,” Molitor said. “I can’t tell you [what it’s like] to come in here and have to try to endure these four games. The first one and third one were not pretty. There was the rain night. We hung in there today, with Ervin’s help.”