Mariners claim RHP Isaac Mattson, OF Grant McCray ahead of free agency opening

The Seattle Mariners have added outfielder Grant McCray off waivers from the San Francisco Giants and claimed right-handed pitcher Isaac Mattson from the Pittsburgh Pirates. These roster moves come just ahead of the official opening of MLB free agency, as the Mariners adjust their 40-man roster. Both players retain minor-league options that can be utilized for the 2027 season.

McCray brings defensive versatility, elite speed, and strong arm strength to Seattle's outfield, despite dealing with high strikeout rates in his major league career. Meanwhile, the 31-year-old Mattson provides bullpen depth with an over-the-top delivery and a high-spin four-seam fastball that generates fly balls, offering support to a Mariners middle relief corps looking for reinforcements.