PORT ST. LUCIE, Fla. -- It was 8:34 on a Sunday morning, Florida's coastal air still refrigerated, when Yoenis Cespedes followed a narrow corridor out of the Mets' clubhouse for a cage session. He grabbed a 42-ounce bat, added a weighted donut to it and used it like to pendulum to stretch his back and shoulders.
As assistant hitting coach Pat Roessler fed him baseballs on a tee, Cespedes moved at quarter-speed, lofting each of them to the upper-right corner of the cage's netting. He stepped away, dropping the donut with a clank, then started swinging the 2 1/2-pound bat with only his right arm. His left arm. Both. His motion remained rhythmic. Quietly, the cage's netting swished as each ball met it.
By this point, hitting coach Kevin Long had finished tutoring one of the Mets' younger hitters in an adjacent cage. Long turned and watched in silence as Cespedes placed a shorter tee next to the larger one, alternating swings at different eye levels. "Watch your back foot," Roessler said, dropping a bat in front of Cespedes' right sneaker to fine-tune his pivot.
For the better part of two years, these drills, these details, have formed the bedrock of Cespedes' ascension from one-dimensional slugger to National League MVP candidate. Now 31, Cespedes is the Mets' best hitter, as much the heart of their lineup as David Wright is the soul of their clubhouse. Back in New York on a four-year, $110 million contract that surprised even manager Terry Collins, Cespedes has developed into a bona fide MVP candidate.
He will need to make good on that promise for the Mets to return to baseball's grandest stage.
"We all have that mentality," Cespedes said through an interpreter. "We know we can win a World Series."
When the Mets traded for outfielder Jay Bruce at the non-waiver Trade Deadline in August, they did so with one eye toward 2017. Concerned about their ability to woo Cespedes back to Queens, the Mets forced themselves not to depend on his return. Collins assumed his best hitter would sign elsewhere.
Only slowly did that skepticism dissipate, as Cespedes proved his love affair with the city was genuine.
Defecting to the United States from Cuba, enduring three trades in a 366-day span, feeling itinerant throughout his baseball life -- all of that ate at Cespedes, say those close to him. He longed for the type of permanence he came to discover in Flushing, where he had grown fond of his teammates -- Jose Reyes and Asdrubal Cabrera, in particular, became outsize influences -- and staff members-turned-friends. Cespedes told his agents as much: He did not want to start over again.

"He was gung-ho about really making sure that he was a Met for the long haul," said Kyle Thousand, head of Roc Nation Sports' baseball division. "It's rare in this game to find a player who can really excel on the field in New York, and handle the pressure and scrutiny that comes along with it. Yoenis is just that type of player."
When Cespedes signed his four-year commitment to stay put, Mets executives rejoiced. Collins exhaled. His trump card was back.
During the summer, Cespedes spends at least an hour each day in the batting cage. He obsesses about details there, using drills learned mostly over the past two seasons.
The most useful, Cespedes said, is an exercise in which he places three baseballs over home plate in a diagonal line. As Roessler throws him soft tosses, Cespedes uses the balls as guidelines to burn the strike zone into his brain, forcing himself to differentiate between a ball on the inside corner and one just off it.
It is no accident that Cespedes swung at only 47.6 percent of all pitches last season, the lowest amount of his career. Laying off roughly two-thirds of all pitches outside the strike zone, Cespedes nearly doubled his walk rate to a career-high 9.4 percent. His on-base percentage spiked to .354, best since his rookie season. And Cespedes did all that without sacrificing power; his .530 slugging percentage and 31 homers both ranked ninth among NL hitters.
"It wasn't natural for him to go up there and kind of take pitches and be aware, and understand what opposing pitchers are trying to do to you," Long said. "But at the end of the day, he trusted in the process. … The difference is a good hitter to a great hitter."
For his efforts, Cespedes finished eighth in MVP voting. A higher standing is something he craves; Cespedes strives to win the thing, and he might as well supplement that with an Esurance Best Major Leaguer trophy and a Silver Slugger. While Cespedes has made it clear, on followup, that a World Series victory is his ultimate desire, his individual success seems like a prerequisite.
So Cespedes is working at excellence, understanding that this is not a finished product. He recalls what Madison Bumgarner did to him in the Mets' 2016 NL Wild Card loss, exposing a weakness on balls just north of the strike zone. He knows the health of his legs, an issue last summer, remains paramount. He figures he can't be perfect, but he's trying. Earlier this spring, when Cespedes lofted a deep fly ball that he thought should have left First Data Field, he asked the clubhouse staff to order him a new set of bats.
Cespedes and Long were joking about that episode last week when Collins walked into the batting cage area, rapping his left fielder twice on the shoulder.
"How's it going, pal? You all right?" the manager asked in greeting.
The Mets' 2017 season may just depend upon the answer.