PORT ST. LUCIE, Fla. -- It was evident right from the start of Chris Flexen's first major league stint that he wasn't ready yet. The Mets were starting to trade away their veterans and all of their pitchers were injured. So, Mets general manager Sandy Alderson made the call to Double-A and had one of their best right-handed starting pitching prospects flown out to San Diego to make his debut.

Flexen's pitch count rose in the first inning and he was hit hard. After three innings, manager Terry Collins had seen enough.

His next few starts went about the same. He was knocked around in Colorado, he won a couple games behind some big leads but then he gave up seven earned runs in Cincinnati and Houston and was then finally removed from the rotation.

Flexen pitched in 14 games going 3-6 with a 7.88 ERA. He had given up just nine earned runs combined in High Class-A and Double-A before his July call-up. This rushed development was the result of a farm system in a state of disarray and a rotation that just couldn't stay healthy last year.

And this rushed development could have ruined some prospects. It has ruined some prospects in the past. But not Flexen, a player who is always determined to see the positive in everything.

For him, this was just about the best learning opportunity he could have asked for.

"Every outing, success or failure was a big learning opportunity," Flexen told NJ Advance Media. "You're not going to get that at that level anywhere else. I think the biggest thing for me that I learned about myself was that I do have what it takes to be there. I had some success along the way, but it took some some bumps and bruises and well."

The 23-year-old Flexen learned what a lot of pitchers learn around his age: He learned a feel for pitching.

"He looks a lot more confident," his catcher in Binghamton, Mets prospect Tomas Nido said. "Confidence is everything. If he's got confidence, that's all he need. Because the ability is there, the pitches -- everything else is there."

What Flexen does is throw strikes. Even as a rookie who was straight from Double-A, he wasn't afraid to attack hitters. Which is exactly what new Mets manager Mickey Callaway wants to see. He wants his hitters to own the inside part of the plate and never back down to a challenge.

Flexen's fastball isn't exceptionally hard, and though he's touched the mid-90s a few times this spring, he's not worried about how hard he's throwing. Through five innings of Grapefruit League play, he's allowed one earned run and struck out four. That zero in the walk column is something he's especially proud of and thinks a more refined changeup has helped him finish off hitters.

But the biggest thing that helped the Mets' 14th-best prospect was the success he had in the big leagues last year.

"I think actually going into the bullpen kind of helped me reset everything," he said. "I came back out and felt like myself again."

What comes next for Flexen is a challenge, because pitching in Las Vegas is always a challenge, but it's not quite as difficult as what he did last year. The Mets went out and signed more starters and bolstered their major league and Triple-A depth.

Perhaps they learned a lesson too. Now, they don't have to rush prospects like Flexen.

For Flexen, that means he may not get a chance to make it back to the big leagues until September. But this is far from a disappointment for a kid who rarely seems rattled. This is just another chance to learn and grow, so he can get to the place where he wasn't last year but hopes to be this year: Major league ready.

"It's easy to get away from yourself, but like I said, it was all the biggest learning process," he said. "And that was the biggest lesson -- how to maintain that confidence throughout, whether you're having success or not."

Abbey Mastracco may be reached at amastracco@njadvancemedia.com. Follow her on Twitter @abbeymastracco. Find NJ.com on Facebook.