One of the worst years of Justin Verlander’s career came in his ninth full season in the big leagues in 2014.

It started with core muscle surgery, the effects of which lingered throughout the year and forced him to compensate with his mechanics, leading to shoulder issues. It included the shortest start of his career, after which he feared his career might be over. And it ended with a 4.54 ERA, his 104 earned runs allowed the most of any pitcher in the American League.

It also helped plant the seeds that changed the rest of his career, which will continue in Queens for at least the next two seasons after the Mets on Monday signed Verlander to a two-year, $86.6 million contract that includes a vesting option for a third year at $35 million.

Investing that much money in a pitcher who will turn 40 in February comes with risks, but Verlander used one of the lowest points of his career to help get ahead of them. After his rough 2014 season with the Tigers, he began to take better care of and get better in tune with his body, his knowledge of which is unmatched, according to those who have worked closely with him.

“There’s no magic bullet,” said Annie Gow, a physical therapist who started working with Verlander after the 2014 season. “He wasn’t graced with an amazing whatever — he works hard at it. Everything he has gotten, it’s through hard work. But I think he understood he needed to take care of himself in that offseason phase. Build the strength, get your mobility.

“He just changed his way of being.”

That same offseason, Verlander began working with pitching guru Ron Wolforth, who helped get his mechanics back on track after they had been thrown off while compensating in the aftermath of his core muscle surgery.

Wolforth described Verlander as a “kinesthetic genius” for his strong sense of how his body is moving. But that movement pattern had gone off course in 2014, and Verlander struggled as a result, in addition to experiencing shoulder soreness and a startling decrease in velocity. He bottomed out in a one-inning start that August in Pittsburgh, leaving him worried that his career might be over, he later told MLB.com.

“His arm was dragging,” Wolforth said. “It was kind of out of sequence slightly because of the injury. He tried a different organization, and it got really draggy and put extra stress on his anterior shoulder, medial elbow, and also it really limited him, for the first time in his career, on his recovery.”

So Wolforth worked with Verlander on getting back to his old form — the one that won a Cy Young and MVP in 2011 — by looking at video from his past seasons and giving him tips and tools (including a connection ball, which sits between his forearm and bicep to help align his arm properly) to get him back in sync.

Then, with some help from then-girlfriend, now-wife Kate Upton, Verlander also found a personal trainer in the Los Angeles area, Peter Park, who honed in on improving his mobility, core work and fitness.

When he first started working with Verlander, Park saw an athlete who was not very mobile and “wasn’t put together very well after playing so many years.”

“He’ll probably kill me for telling you this, but I was surprised — I had junior high kids that were stronger than him in the gym, in the upper body,” Park said. “His legs were always strong. But it was ridiculous how fast he got strong, once he was doing the right stuff. Just because his work ethic is so good.”

Park’s initial assessment of Verlander was similar to the one from Gow, the New York City-based PT who saw a then-31-year-old that had a “dysfunctional system” that “was not working optimally.”

At first, Verlander wanted to tell Gow what to do, but she told him she did not work that way. She wanted to take a whole-body approach instead of just focusing on his shoulder. Gow described Verlander’s feet as “cement blocks,” which were “manifesting in his hips and up into his shoulder.”

“So basically, we took him apart and put him back together again,” Gow said with a laugh.

With all three specialists, Verlander was not interested in just getting their advice, taking it at face value and moving on. He wanted to know why they suggested the exercises or regiments they did and how it was going to make him better, constantly giving his own feedback in the process. But once he realized how much better he was feeling, he bought in.

“I would say Justin Verlander is very skeptical,” Wolforth said. “He’s not cynical. He’s very skeptical. I think that’s probably one of the reasons he’s so good.”

As for the on-field results of his off-field work? Verlander has pitched better every year since, defying the typical aging curve. He finished second in Cy Young voting in 2016 and 2018 before winning the award for a second time in 2019.

Then, after throwing just six innings between 2020 and 2021 because of Tommy John surgery, Verlander turned in arguably the best season of his career in 2022. At the age of 39, he posted a 1.75 ERA across 175 innings, winning his third Cy Young award as the fourth-oldest pitcher to do it.

“I just think [Tommy John surgery] rebooted him,” Park said. “Now, he’s starting the second journey almost, like the 2.0.”

Along the way, Verlander has built a team around him that has played an important part in his success and longevity. He can and will text, call or FaceTime Gow, Wolforth and Park when any issues pop up during the course of a season or offseason. He knows his body well, but when he needs an extra set of eyes or ears, they are quick to help.

At least for the next two years, the Mets hope to reap the benefits of that work Verlander has put into properly preparing his body for the 162-game (and more) grind, which has allowed him to continue pitching at an elite level, regardless of age.

“Of course Father Time is going to catch up eventually,” Park said. “You can’t be 70 and be pitching 98 mph. It’s got to catch up somewhere, but he’s just one of those, kind of like the Tom Brady of baseball. He just somehow figures out how to [keep going].

“He’s just constantly learning about himself. He just doesn’t leave any stone unturned.”