Third baseman Matt Chapman and the San Francisco Giants agreed to a six-year, $151 million contract extension late Wednesday, keeping the veteran from opting out of his current deal to reach free agency.

The deal, which starts in 2025 and replaces the last two years of a three-year, $54 million contract he signed earlier this year, includes no deferred money and a full no-trade clause, sources told ESPN. The deal will expire in 2030, when Chapman will be 37.

Chapman, 31, has been one of the most productive players in baseball this season, combining a powerful bat with the best third-base defense in the major leagues. And less than a year after his market in free agency cratered, Chapman parlayed his strong season into a significant pay day -- and guaranteed himself more than $170 million between this season and the end of the extension.

It's a stunning turnabout from the winter, when Chapman's free agency dragged and landed him in San Francisco. All three years of his contract included opt-outs at the end, and Chapman went into spring training saying he wanted to bet on himself rather than take a lesser long-term deal.

The bet paid off.

"This offseason was a little strange with the free agent market, but I was willing to bet on myself," Chapman said during a news conference Thursday. "I believed in myself. I believed that the Giants would see my value as the season went on and what I bring every single day."

Chapman was scratched from the starting lineup Wednesday, missing just his fourth game this season to work on finalizing the contract.

"Obviously, it was pretty important to get this thing done," Chapman said. "We got it done, and now chances are I'm not going to be watching very much."

Chapman was back in the lineup on Thursday, batting cleanup against Arizona. Giants manager Bob Melvin, who also managed Chapman in Oakland, said that the 31-year-old has become a clubhouse leader.

"We have some younger guys here that are learning their way and developing right now, and they watch the way he plays the game," Melvin said. "There's an expectation of how it needs to be played and he's setting the example of that and guys have to fall in line."

With a .247/.333/.445 line, Chapman has an adjusted OPS 21% better than league average. His 22 home runs and 56 extra-base hits lead the Giants. And his glove, golden four times already, could be platinum-worthy this season.

All of it put him near the top of wins above replacement leaderboards throughout the game. His 6.0 Baseball-Reference WAR are the ninth most in baseball. At FanGraphs, it's 4.5 WAR, 13th among position players. It's reminiscent of the seasons that gave Chapman his first two Gold Gloves and his only All-Star appearance.

When he arrived in Oakland in 2017, Chapman had showcased power in the minor leagues that later would put him among the game's exit-velocity giants. Chapman's ability to hit the ball extremely hard -- he's 98th percentile in bat speed and 96th in average exit velocity -- has persisted, and it gave the Giants the sort of confidence to pay him late into his 30s.

It was also a deal of necessity. At 68-72, the Giants are again one of baseball's most disappointing teams. San Francisco has settled around .500 each of the past three seasons after a 107-win campaign in 2021, and it has left fans disenchanted and loud about potential changes inside the organization.

With president of baseball operations Farhan Zaidi negotiating the contract with Chapman's agent, Scott Boras, he doubled down on one of the successes of his winter. Another, left-hander Blake Snell, is likewise a Boras client expected to opt out of his deal and sign for a significantly larger number than the $60 million San Francisco guaranteed him for two years over the winter.

"The game rewards players like this," Boras said.

Zaidi said conversations with Chapman began two to three weeks ago.

"We're a team that's trying to compete every year," Zaidi said. "When we have an opportunity to get a great player who's willing to bet on himself, that's always an attractive proposition to us. And that's what Matt did. He bet on himself and he got a very deserving reward today."

Zaidi did not engage Thursday when asked about questions surrounding his future with the Giants.

Chapman joins a core that now includes right-hander Logan Webb (signed through 2028), center fielder Jung Hoo Lee (2029) and a cadre of young players who have shown flashes of excellence at points throughout the season: center fielder Heliot Ramos, catcher Patrick Bailey, shortstop Tyler Fitzgerald and left-hander Kyle Harrison.

A California native, Chapman said he feels comfortable in the Bay Area. He batted back concerns that San Francisco is not an attractive place for free agents, sharing that other players have reached out about joining the Giants after news of his new deal.

"I don't think it's going to be a hard sell," Chapman said. "This organization is amazing. They do everything they can for the players. We have a lot of good players. I think that we're going to continue to build here. I think that people will see that from the outside and I don't see that ever being an issue."

Now that Chapman is off the market, a free agent class not teeming with high-end offensive options thins out even more. New York Yankees outfielder Juan Soto is the prize of the group, and after Chapman's signing, third-base-hungry teams will turn their attention toward another Boras client, Alex Bregman. Teams that could be in the market for a third baseman include Bregman's current team, Houston, as well as the New York Mets (if Pete Alonso leaves and Mark Vientos moves to first), the Yankees, Seattle and Toronto.

Other top free agent bats include Alonso, Milwaukee shortstop Willy Adames, Baltimore outfielder Anthony Santander, Arizona first baseman Christian Walker and Los Angeles Dodgers outfielder Teoscar Hernandez.

The Associated Press contributed to this report.