Quintana, Cooper working to get lefty back on track

Jose Quintana wipes his face during the second inning of a game against the Boston Red Sox Tuesday, May 30, 2017, in Chicago. (AP)

DETROIT — Jose Quintana’s unforeseen poor start is a head-scratcher, what with the left-hander’s steady career track record, that dominating performance in the World Baseball Classic to kick off his 2017 season and his first-rate work ethic.

Adding to the mystery is what pitching coach Don Cooper sees when Quintana throws between starts in the bullpen — the same precise Quintana he always has known.

“His sidelines are impeccable,’’ Cooper said Sunday.

It might be grasping at straws, but one national baseball writer recently speculated that Quintana might not be 100 percent physically. The Sox do have six pitchers on the disabled list.

But Quintana on Sunday said to scratch any health-related hypothesis off the list of possibilities why he was lit up for seven runs in 2‰ innings against the Red Sox in his last start and eight runs in 4„ against the Diamondbacks in the one before that.

“I feel good, my arm is good,’’ Quintana said Sunday.

“He feels good. He’s throwing good,’’ Cooper said. “If you were there to watch all the sidelines and stuff, you would say it’s just a matter of time for this guy.’’

Fastball command has been the bugaboo for the 2016 All-Star, who will take a 2-7 record and 5.60 ERA into his next start Tuesday at the Rays, trying to stop a Sox losing streak that increased to five games with a 7-4 loss to the Tigers at Comerica Park.

Quintana is supposed to be the Sox’ ace, which means he’s supposed to stop skids such as these, but he hasn’t looked the part since Chris Sale was traded in December.

“He’s making some mistakes, and he’s been paying for those mistakes,’’ Cooper said.

In his bullpen session with Cooper after the most recent outing, Quintana said he might be on to something, working on getting more arm extension through the finish of his delivery.

The fastball, not overpowering at 92-93 mph, has been getting too much of the plate, sometimes up in the strike zone, and often when he works from the stretch.

“The delivery is the same,’’ Quintana said. “I don’t finish a couple of times. That’s it.’’

Speculation also runs high that trade rumors that have followed Quintana since the Sox went into rebuilding mode are affecting him. Quintana said — once again — that trade worries are not in his head. But Cooper can’t dismiss it.

“Good question,’’ Cooper said. “You don’t know. There’s no measuring stick for that. We can’t go on that, I’m not thinking that. Who knows?’’

As Cooper pointed out, the “900 no-decisions [61 in fact, thanks largely to poor run support during his career]” haven’t affected -Quintana. He’s as steady as they seem to come.

“He has a good head on his -shoulders,’’ Cooper said. “He’s just really always focused on the next. I don’t care who you are, you are going to have moments where it doesn’t work out. He’s had his share, and now hopefully we are back on the good foot.

“Not every bad pitch you make gets hit, but it seems like the ones he’s been throwing have. He’s still the same guy. You are going to see him soon, and hopefully it’s this next start.

“So we expect bigger things from him, too. He’s trained everybody that he’s a quality-start machine, and it’s not happening so everybody wants to know what’s going on.’’

Quintana wants to figure it out, too. He remains upbeat, as focused as ever, and is eager for Tuesday.

“I stay hungry, and I want to eat,’’ Quintana said with a smile. “I want to compete.”

Follow me on Twitter @CST_soxvan.

Email: dvanschouwen@suntimes.com