The Mariners acquired Santana and cash considerations from the Royals on Monday in exchange for right-handed pitchers Wyatt Mills and William Fleming.
Santana had produced a below-average batting line in both 2020 and 2021 and looked to be set for his third straight subpar season this year, but a .357/.478/.554 run thus far in June has dragged his wRC+ up to 104. That's still a pretty uninspiring mark for a first baseman, but he should have a path to at least short-term playing time with Ty France out with a flexor strain. He could still start frequently as a designated hitter once France returns, but he's unlikely to be a particularly interesting fantasy option. The Royals called up top prospect Vinnie Pasquantino to take Santana's place on the roster and step in as Kansas City's everyday first baseman.