PITTSBURGH — Scott Diamond can’t quite put his finger on it, but something feels off after the rookie left-hander’s hot start made him one of the few pleasant surprises for the Minnesota Twins.

The same could be said for the rest of his teammates.

Diamond labored through 5 1-3 largely ineffective innings in a 7-2 loss to the Pittsburgh Pirates on Tuesday night. He has dropped two straight decisions, and the Twins have lost five of six.

“I definitely was battling all night and just really wasn’t executing that well,” said Diamond (5-3). “I left a lot of pitches over the middle and up, and when that happens you get hit pretty hard.”

The Pirates took full advantage.

Kevin Correia (3-6) tossed 5 1-3 scoreless innings to win at home for the first time in nearly a year.

“I feel like I’ve thrown a lot better than last year at home,” Correia said. “I knew the (wins) would come. We’re starting to hit.”

The Twins, not so much. Minnesota began the night with the highest batting average in interleague play (.306) but mustered little against Correia.

Correia was an All-Star last year after earning 11 wins before the break, but since then has been in an 11-month funk — winning only three of his previous 20 starts, dating to last July. None of those came at home, where he had been 0-6 since beating the Orioles on June 22, 2011.

For one night anyway, Correia looked comfortable in the home jersey. Though hardly overpowering, Correia kept the ball away from the middle of the plate while grinding through 97 pitches.

Correia’s only trouble spot came in the sixth inning, when a walk and a single put runners on the corners with one out, and he gave way to Tony Watson. The Twins loaded the bases before Watson struck out former Pirates catcher Ryan Doumit to end the threat.

Diamond wasn’t nearly as crisp. The 25-year-old pitcher has been one of the few good stories this season for the underachieving Twins. He won five of his first seven starts thanks to impeccable control.

He had issues in a loss to the Phillies last week and kept the ball in the strike zone a little too much against the Pirates, who no longer look like one of the weakest offensive teams in the majors while lifting Diamond’s ERA from 2.13 to 2.57.

“Something doesn’t feel completely right after that (hot) start and I think it’s just a little bit of work in the pen,” Diamond said. “I’ve got to refine the curveball a little bit, too. It just wasn’t coming out right today.”

Pittsburgh, which was last in nearly every major statistical category for the first two months of the season, is third in the National League in runs scored in June, adding to the total on a night the ball had little trouble carrying through the oppressive heat.

Harrison gave the Pirates a 1-0 lead in the first with help from Minnesota leftfielder Josh Willingham. Harrison smacked Diamond’s fastball toward the wall in left.

Willingham initially broke forward before giving chase. He leaped just as the ball caromed off the top of the wall. Instead of grabbing it, however, Willingham could only watch as the ball deflected into the stands for Harrison’s second homer of the season.

“I didn’t realize it,” Willingham said. “Somebody told me, but it really didn’t hit me hard enough because I ran into the wall at the same time.”

Gardenhire didn’t challenge the call, though maybe he would have if there was expanded replay in baseball. The hit was not reviewable.

“From our viewpoint it looked like a home run,” Gardenhire said. “Maybe we need instant replay. Give me a red flag and I’ll throw it out there.”

Casey McGehee’s sacrifice fly in the fifth gave the Pirates a 2-0 lead, and Pittsburgh pushed it to 4-0 an inning later. Barmes, who lifted his batting average to .200 for the first time this season, doubled in Pedro Alvarez, and Matt Hague grounded into a fielders’ choice.

Span’s two-run homer briefly made it interesting before McCutchen responded with a two-run shot of his own.