SAN DIEGO — Jeff Locke’s tough outing may have put his next start for the Pirates in question.

Odrisamer Despaigne pitched eight strong innings and Will Middlebrooks homered and drove in three runs in the San Diego Padres’ 7-1 win over Pittsburgh on Sunday night.

Despaigne (3-3) shut out the Pirates through six innings before Gregory Polanco hit a solo homer off him in the seventh.

The night was a complete bust for for Locke (3-3). The Pirates lefty lasted just four innings, allowing seven runs — six earned — and eight hits. He had not allowed a run in 10 2/3 innings over two starts coming in, but overall, he has not been consistent.

“We just feel behind too many people tonight and were forced to make pitches in hitters’ counts and they put some good swings on some balls,” Locke said.

“He’s not throwing enough strikes to be effective,” Pittsburgh manager Clint Hurdle said. “He threw out of the stretch 75 percent of his pitches. When you’re not throwing strikes, and with his ball-strike ratio, you have no safety net.”

When asked if Locke might be replaced in the starting rotation, Hurdle said: “I’m not going to do any hypotheticals. I just want to make sure we look at what Jeff Locke is doing first.”

If Hurdle is thinking about making a change, reliever Vance Worley made a great case by throwing four scoreless innings while allowing five hits and striking out four.

Despaigne gave up seven hits, struck out four and walked one in his longest career outing.

The Cuban-born righty has allowed just three runs over 20 innings in his last three starts.

“Overall, my stuff was good, I was hitting my spots, my command was good,” Despaigne said. “I think I was able to hit the corners.”

Middlebrooks homered off Locke in a three-run third inning and added a sacrifice fly in the fourth.

Jed Gyorko had a two-run single in the first inning and Clint Barmes had three hits and an RBI.

It was the Padres’ fourth win in six games after having dropped eight of 10.

The Padres won at home for just the third time in 10 games. After going 48-33 at Petco Park last season, San Diego is just 13-14 this season.

In Clint Hurdle’s five seasons as manager, the Pirates have never had a losing record in May. Despite the loss Sunday night, Pittsburgh finished May with a 14-14 mark.

Despaigne has been tough on left-handers, limiting them to a .212 average coming into the game. Polanco’s home run was the first he’s surrendered to a left-handed batter since Aug. 22, a span of 15 outings.

Locke took a hard grounder off his right foot in the fourth inning. While home plate umpire Jeff Nelson went out to check on Locke, the lefty waved off Hurdle and stayed in the game.