Matt Chapman has played three major-league seasons and has two Platinum Gloves. He’s clearly the American League’s best third baseman, an elite defender in every sense. That’s why he was the 2018 overall defensive player of the year, someone who saves runs (and games) with his glove.
Matt Olson has played two full MLB seasons and has won a Gold Glove in each one. The A’s first baseman is in the Chapman class at his position.
Those two alone wouldn’t make a defense rock solid. A pronounced weakness or two can downgrade a defense in a hurry.