PITTSBURGH -- The Pittsburgh Pirates took plenty of heat from the media and fans when their biggest offseason acquisition following their first postseason appearance in 21 years was right-hander Edinson Volquez.

However, the Pirates are having the last laugh as the veteran right-hander reached double figures in wins in a 4-2 victory over the reeling Detroit Tigers on Tuesday night. The Pirates swept the two-game series against the Tigers.

Volquez (10-7) allowed two runs and five hits with five strikeouts and two walks to win his second start in a row and win for the fourth time in his last five starts at PNC Park.

He looks like a bargain now after being signed to a one-year, $5 million contract as a free agent in December after having a 5.71 ERA -- the highest of any major league qualifier for the earned run average title -- last season with the San Diego Padres and Los Angeles Dodgers.

"It's a big pat on the back for a lot of people in the organization," Pirates manager Clint Hurdle said. "We've got work to do still, he's got work to do still, but give him a lot of credit because he used his ears, used his eyes and made some adjustments to become a better pitcher."

The Pirates (64-55) won for the fifth time in their last seven games and lead the National League wild card standings. They also cut the Milwaukee Brewers' lead to 1 1/2 games in the NL Central.

The Tigers (63-54) lost their fourth straight game and sixth in the last seven games. They are one-half game behind the Kansas City Royals in the American League Central.

Pirates left fielder Travis Snider had two hits, including an RBI double that capped a two-run third inning that put the Pirates ahead for good. He went 5-for-9 in the series, which were the first two games after Pirates center fielder and 2013 NL MVP Andrew McCutchen was placed on the disabled list.

"It's always the perfect day when the team wins and you make a contribution," Snider said. "At this point, you can take an 0-for-4 and still feel good if the team wins because it means you've gotten one step closer to where you want to go."

Left-handers Justin Wilson and Tony Watson and closer Mark Melancon, who notched his 22nd save, each pitched one scoreless inning of relief for the Pirates.

Rookie left-hander Robbie Ray (1-2), who was recalled from Triple-A Toledo before the game by the Tigers, took the loss. He lasted five-plus innings and gave up four runs and six hits while walking two and striking out five.

"I thought I threw the ball pretty well," Ray said. "I gave up a couple of doubles on a broken-bat hit down the line and a ball that just snuck past (first baseman Miguel Cabrera)."

Ray is expected to remain with the Tigers at least through the end of the week as he likely will fill in Sunday against the Seattle Mariners for right-hander Justin Verlander, who is nursing a sore shoulder.

Verlander's injury was one of the many bad things that happened on the Tigers' 2-7 road trip.

"It was a crappy trip," Detroit manager Brad Ausmus said. "In a couple of weeks, we'll look back and laugh on it."

Tigers catcher Alex Avila had two hits, including a homer.

NOTES: Detroit RHP Justin Verlander underwent an MRI on Tuesday in Detroit and it revealed no structural damage in his shoulder, just inflammation. He left Monday night's loss at Pittsburgh after one inning because of a sore shoulder and is doubtful for his scheduled start Sunday against Seattle, though the Tigers are hopeful he will avoid going on the disabled list. ... Detroit recalled LHP Robbie Ray and LHP Blaine Hardy from Triple-A Toledo, optioned RHP Justin Miller to the same club and placed RHP Anibal Sanchez (strained right pectoral) on the 15-day DL, retroactive to Aug. 9. Ray started Tuesday and will pitch Sunday if Verlander cannot pitch. ... Pittsburgh recalled RHP Brandon Cumpton from Triple-A Indianapolis to pitch out of the bullpen and optioned RHP Casey Sadler to the same club. ... Pirates RHP Gerrit Cole (strained right lat) will make a fourth rehab start for Indianapolis on Saturday and is scheduled to pitch seven innings while being on a 90-pitch limit. ... The teams will switch venues Wednesday night and play at Comerica Park in Detroit. The Tigers will call up RHP Buck Farmer from Double-A Erie to start and make his major league debut against Pittsburgh RHP Vance Worley (5-1, 2.30).