SAN FRANCISCO -- To the Giants, signing first baseman Brandon Belt to a six-year, $79 million contract Saturday was all about preserving their nucleus.
Players drafted by the Giants and developed in their Minor League system, including Belt, have contributed handsomely to San Francisco's six winning records in the previous seven seasons. That span, of course, featured three World Series titles.
With his new deal, Belt joined shortstop Brandon Crawford and catcher Buster Posey, two other pillars of the Giants' roster, in the club's select group of players who are signed through 2021.
"To say I'm grateful is an understatement," Belt said.
The Giants basically bought out Belt's final years of eligibility for salary arbitration, as well as free agency.
"He's one of our guys," Giants manager Bruce Bochy said. "He's one of our core players."

Second baseman Joe Panik and third baseman Matt Duffy also fit the profile of players whom the Giants might someday try to lock up contractually. There are a handful of recent precedents for this, most notably the New York Yankees' contingent of shortstop Derek Jeter, catcher Jorge Posada, left-hander Andy Pettitte and closer Mariano Rivera, who was signed as an amateur free agent.
"It's easier said than done but finally, especially from a position player standpoint, all of the sudden we've got a core group," Giants executive vice president of baseball operations Brian Sabean said.
Belt, who turns 28 on April 20, has never hit 20 home runs, driven in as many as 80 runs or batted .300 -- statistical levels that reflect Major League competence, at least to old-school observers.
Belt's credentials shine brighter through more modern standards. In a news release to herald Belt's signing, the Giants pointed out that Belt's .355 on-base percentage since 2012 was exceeded only by six other first basemen: Joey Votto (.443), Paul Goldschmidt (.402), Prince Fielder (.390), Freddie Freeman (.373), Edwin Encarnacion (.363) and Anthony Rizzo (.362).
"He's been one of the best first basemen out there for the past five or six years," Bochy said.

Belt believes he's poised to achieve the consistency that has eluded him.
"For me, what it comes down to is experience," he said.
Giants general manager Bobby Evans pointed out that retaining homegrown performers such as Belt is preferable to the risk of seeking players through other means.
"What you give up to acquire players in a trade -- is that going to be better than what you have? Same with the free-agent market," he said.
Belt's signing eliminates the possibility of Posey moving to first base, which has been a favorite topic of speculation -- though Evans noted this never was discussed within the organization. Evans emphasized the Giants want Posey to be the team's "quarterback," leading them from behind the plate and in the middle of the batting order.
Belt's agreement will pay him $6.2 million this year, $8.8 million next year and $16 million annually from 2018 through 2021.