Mets hope righty can Flex’ staff into shape

SAN DIEGO — Chris Flexen spent most of his first major league spring training rehabbing from surgery to remove a bone chip in his knee and never got a real opportunity to strut his stuff for the Mets.

But the 23-year-old pitcher left an impression on club officials, nonetheless.

“He’s got a strong will,” pitching coach Dan Warthen said. “Tough. He wants to be very good.”

Flexen’s chance — the one he never received last March in the Grapefruit League — will come Thursday night against the Padres at Petco Park, where he will make his major league debut for a Mets team short on arms.

Zack Wheeler’s placement on the disabled list this week with a stress reaction in his right arm created a vacancy in the rotation the Mets felt uncomfortable filling from the ranks at Triple-A Las Vegas. So team brass dug deeper, to Double-A Binghamton, where the right-hander Flexen was 6-1 with a 1.66 ERA and 0.72 WHIP in seven starts after beginning the season at Single-A St. Lucie.

“The biggest thing is going to be to manage the emotions — everything is going to be heightened at that moment,” Flexen said. “Whatever got me here, stick with it, and that has been the game plan from the beginning: Being confident, attacking guys and being aggressive and that is what I’m going to go out and do.”

Flexen, who stands 6-foot-3 and 250 pounds, throws his fastball in the 95-96 mph range, according to manager Terry Collins, and has shown proficiency with his slider.

“I saw him in spring training before he hurt his knee, he’s got a very good arm,” Collins said. “I never saw Robert Gsellman until he came up last year, and I’m hearing the same things on Chris Flexen. Good movement on his fastball, keeps the ball down. I’m anxious to see him.”

Gsellman arrived to a hurting rotation last August and teamed with another unheralded righthander, Seth Lugo, to help resurrect the Mets over the final six weeks, when the team rallied to a 27-13 finish to clinch a National League wild-card berth.