Santana was a surprise, in part, because how many players are non-tendered with a batting average of .253 with 21 home runs and 69 runs batted in, along with missing the last month and a half with a shoulder injury. His shortcoming was his defense. He began the season as the Mariners left fielder where his defense was poor at best.
The Mariners moved him back to right field in May, moving Mitch Haniger to center field, which was short-lived because he was injured missing the rest of the season.
The Mariners could have inserted Brandon Bishop into center field however he was injured right after Haniger.