Over 121 games, the 27-year-old Santana hit .253/.329/.441 with 21 homers and eight steals.
Santana was acquired from the Milwaukee Brewers last winter in exchange for outfielder Ben Gamel and minor-league pitcher Noah Zavolas. The slugging outfielder is now two years removed from clubbing 30 homers over 151 games in 2017.
Beckham, 29, posted a .237/.293/.461 slash line over 88 games before receiving an 80-game suspension for testing positive for performance-enhancing drugs.
This is the second consecutive year that Beckham has been non-tendered. The shortstop hit free agency last winter after the Baltimore Orioles cut ties with him, resulting in the Mariners signing him to a one-year, $1.75-million contract. Beckham was projected to land $3 million in arbitration this winter, according to MLB Trade Rumors.