CHICAGO -- Anthony Rizzo was there for the rebuilding years prior to when the Cubs grew into a regular postseason participant. The first baseman was there for the franchise's World Series triumph four years ago and remains a key part of the culture and core.

On Saturday, the Cubs took the anticipated step of picking up Rizzo's $16.5 million option for 2021, keeping him in the fold as the franchise balances winning now with planning for the future. The core group will be much discussed in the coming weeks and months, as Chicago examines its roster needs and payroll realities.

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"The only thing I can acknowledge is that we're in a period of great uncertainty," Cubs president of baseball operations Theo Epstein said at the end of the season. "That's industry wide."

The decision on Rizzo comes one day after the Cubs declined a $25 million option on veteran lefty Jon Lester and instead paid a $10 million buyout. The Cubs also declined a $3.5 million option (paying a $1 million buyout) on veteran utility man Daniel Descalso on Saturday, giving the North Siders 10 Major League free agents at the moment.

Among the Cubs' needs this winter are improving the rotation's depth, finding ways to enhance the offense and adding more relief options. One path will be to target cost-effective free-agent moves, while another is to find players with multiple years of control. The avenue for accomplishing the latter is via trade.

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That is where Chicago's core comes into play. Barring any extensions, the Cubs have four key players -- Javier Báez, Kris Bryant, Kyle Schwarber and Rizzo -- poised to hit free agency next winter. Willson Contreras would then be eligible for free agency after the '22 season.

Báez, Bryant, Contreras and Schwarber are part of a robust arbitration class this winter, and those four could net in excess of $50 million combined. Breakout center fielder Ian Happ is also in this offseason's arbitration class, which could shrink via trades in November as the Cubs (and other teams) plan for the Dec. 2 non-tender deadline.

The Cubs know the cost for the 31-year-old Rizzo, whose option year is good value even in an uncertain financial climate. Prior to a subpar showing in '20, Rizzo slashed .276/.379/.499 with nearly 30 homers, 75 walks and 100 RBIs per season over the previous seven years. He hit .222/.342/.414 with 11 homers and 24 RBIs in 58 games during the pandemic-shortened '20 campaign.

Rizzo is a three-time National League Gold Glove Award winner and is a finalist for that award again this year. Beyond his sound offense and steady defense, the first baseman is also a leader behind the scenes, and he is proactive with his various charitable initiatives away from the diamond through his foundation and the club.

After the Cubs were eliminated from the playoffs by the Marlins in the NL Wild Card Series, Rizzo was asked if change felt inevitable for the Cubs' core going into 2021.

"It's so early," Rizzo said. "Who knows where the game's going to go, where this country's going to go, where life's going to go? Baseball next year seems so far away right now. ... I know for a fact [Cubs chairman Tom Ricketts] wants to put a winning team on this field. And our fans deserve it, the city deserves it.

"And we have a lot of guys in this clubhouse that have helped us win and can continue to help us win. So, I know Theo and everyone top to bottom will be putting the best product on the field and do what's best for this organization."