Seattle made the move before Wednesday's series finale against Boston. Ramirez struggled with control in his start Tuesday night, walking five and lasting just 4 1-3 innings.
The decision to recall Maurer, who has transitioned from being a starter to pitching in relief, indicates another roster move on the horizon for Seattle. Ramirez's next turn in the rotation would have come Monday at Houston.
Maurer made seven starts earlier in the season for Seattle, going 1-4 with a 7.52 ERA. He was 1-0 with a 2.79 ERA and three saves in his time as a reliever with Tacoma.