PORT ST. LUCIE, Fla. - By Opening Day, the Mets could have two cornerstone players locked up to long-term commitments.

Gold Glove centerfielder Juan Lagares is on the brink of agreeing to an extension, a source confirmed Wednesday. According to Yahoo Sports, the four-year contract will be worth $23 million. It covers all of Lagares' arbitration-eligible seasons and also includes a club option to buy out his first year of free agency.

"We've got a lot of confidence in Juan and where he is currently,'' general manager Sandy Alderson said. "And where he may end up being as a player in the future.''

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Lagares' deal comes in the wake of the Mets' engaging in extension talks with power-hitting first baseman Lucas Duda, who has set Monday's Opening Day as an unofficial deadline before talks are shelved for the season.

Duda's deal also likely would run through his first season of free agency.

"We look for good players, and the deal has to be attractive to both sides,'' Alderson said. "And I think if we check those boxes, then maybe something happens with Lucas.''

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With the extension talks, the Mets have shown a willingness to assume some risk, pledging guaranteed money to each player despite the threat of decline. But the rewards could be beneficial for the budget-conscious Mets, especially if payroll remains in the roughly $100-million range going forward.

The extensions not only provide cost certainty, but also would translate into long-term savings if each player continues to perform as he did last season.

Duda, 29, is coming off his first 30-homer season. Lagares, 26, is fresh off his first Gold Glove award in centerfield.

"I love the Mets," said Lagares, who acknowledged talks but denied an official agreement has been reached. "That's the team that gave me the opportunity when I was 16 years old. They gave me the opportunity to play in the big leagues . . . This is where I want to be.''

Timing has proven to be key in both negotiations.

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According to a source, the Mets sensed an opening with Duda, who has two arbitration- eligible seasons remaining before reaching free agency in 2018. The Mets apparently sensed the same opportunity with Lagares, who hit .281 in 116 games last season.

According to Yahoo Sports, Lagares' four-year deal would take effect next season, which would be the first of what likely would be four seasons of arbitration eligibility. He reportedly would make $2.5 million in 2016, followed by salaries of $4.5 million, $6.5 million and $9 million.

In 2020, Lagares' first year of free agency, the Mets hold a $9.5-million option with a $500,000 buyout.

By then, it should be clear whether the deal proves to be a bargain. Much of Lagares' value is derived from his defense in centerfield, a premium position because it is one of the most demanding.

The introduction of new technology could bring more precise measurements for defensive abilities. For instance, MLB last season debuted Statcast, which provided details such as the amount of ground covered by a player running down a fly ball. Such measurements could lead to more accurate valuations to players such as Lagares, who has outstanding range.

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In the past, the Mets locked up young players such as Jose Reyes and David Wright before they could reach free agency. The latest example came in 2012, when Alderson signed Jonathon Niese to a five-year, $25.5-million contract that covered his last pre-arbitration season, all three of his arbitration-eligible years, and his first free- agency year in 2016.

In theory, the Mets could approach ace Matt Harvey with a similar extension, although it appears that they have not.

Said Alderson: "Now you're ranging too far afield for me.''

Harvey is represented by agent Scott Boras, whose clients historically have held out for free agency.