FORT MYERS, Fla. — Francisco Alvarez proclaimed the Mets “the best lineup in baseball” shortly after his spring training arrival at Clover Park. The task now is making sure he’s a big part of the reason why.

And in that regard, Alvarez very much remains a work in progress.

You can probably say that about a high percentage of major leaguers with the calendar having just flipped to March. Opening Day is still more than three weeks away.

For Alvarez, however, this isn’t about merely stacking up reps or fine-tuning some trusted mechanics. He underwent what amounted to a swing-renovation this offseason, tinkering with a number of pressure points designed to make him a better all-fields hitter, with last year’s teammate, J.D. Martinez — the resident clubhouse batting guru — pointing him toward an Atlanta-based coach for winter workshopping.

To call this an experimental phase for Alvarez, a young slugger who has already had success in the majors, sounds too alarmist. But it definitely could be characterized as a spring-training project, and Alvarez is going to need every possible Grapefruit League at-bat to get where he wants to be.

With that in mind, Alvarez played back-to-back games during the Mets’ weekend trip along Florida’s west coast, and didn’t have much fun Sunday in their 6-4 loss to the Red Sox at JetBlue Park. He painfully absorbed three hard-hit foul balls behind the plate, then went 0-for-3 beside it, with two groundouts back to the mound and a swinging strikeout.

Sunday’s key takeaway? Alvarez came through in one piece. As for the numbers, they’re still at the mostly meaningless stage. He’s hitting .200 (3-for-15) with three singles and seven strikeouts through six games. But Alvarez, at 23, is still a developing player entering what will be his third full MLB season, so I asked him Sunday when he’d like to see some impactful production.

“I want to see results during the season,” Alvarez said. “Spring training is for working. I know what I’m working on. Sometimes it’s tough for me to do in the game, but I’ll just keep going. I believe in what I’m doing. I really like what I’m doing. So I just got to be patient.”

The objective, according to Mets hitting coach Eric Chavez, is to prevent Alvarez’s hips from flying open too soon, a glitch that made him more vulnerable to off-speed pitches in the past. He’s tried to “quiet” his swing mechanics — holding the bat more upright, hands tighter to his body. Even what seems like a few minor tweaks can feel like an overhaul, but Chavez sees this update as crucial to Alvarez’s development as a hitter, as well as the Mets’ ability to wreck opposing pitchers.

“The hope is that he has more direction going towards the middle and his hips are in a good place,” Chavez said. “That’ll keep him on off-speed pitches a little bit better. He really needs to take the next step in hitting lefties. We have a lineup that we should demolish lefties. A lot of teams get exposed by facing lefthanders or righties, but we have a balance of both, so it shouldn’t really matter. But that’s an area we definitely could do a lot better in. Alvy’s a big part of that.”

Against a typical righthanded starter, Alvarez figures to hit seventh, between Jesse Winker and Jeff McNeil. The way the Mets’ lineup is designed, as Chavez explained, they can alternate righty-lefty basically one through nine, a favorable alignment that protects them through the rungs of an opposing team’s bullpen.

Among that group, however, Alvarez could have the most to prove coming off a down season by his standards. After hitting 25 homers over 123 games in 2023, Alvarez dipped to 11 in 100 despite an OPS-plus that slightly nudged over league-average to 101. From one season to the next, his ground-ball percentage soared from 44.0% to 52.2%. Chavez said that the “gifted” Alvarez will always be lethal due to his bat speed, but this is about doing more consistent damage. And these Grapefruit League games are now crucial to transforming those swing changes into lasting muscle memory.

“It’s timing and feel,” Chavez said. “I keep telling him, trust your work. It’s just seeing velocity changes everything. You can work on whatever you want to in the offseason, but there’s no velocity. There’s no adrenaline. So trust in his work. There’s some little things that we’re trying to navigate through, but he’s very positive and he likes the direction he’s headed.”

Alvarez, by nature, is unfailingly upbeat. Which is why his darkening mood last season was the surest indication that the prolonged struggles were eroding his confidence. It became increasingly difficult for Alvarez to shake off being a drag on the lineup. But now that he’s brought a new swing into camp, it’s like that weight has been lifted.

Going forward, however, Alvarez needs to do his share of the heavy lifting. In a multi-dimensional Mets lineup stacked with perennial MVP candidates, 40-homer mashers and on-base specialists, Alvarez has the potential to be a game-wrecker come Opening Day. He’s a pivotal piece in turning the Mets’ dangerous lineup into a deadly one. But he’s got to get this revamped swing down first.

“I’m not rushing,” Alvarez said. “I feel like I’m in a good position.”

He’ll need to be after putting the Mets on the spot with that February boast. If Alvarez is right at the plate, those words will be prophetic.