Miley was traded to the Mariners on Monday in exchange for Roenis Elias and Carson Smith, Ken Rosenthal of Fox Sports reports.
Miley struggled in his lone year in Boston after being traded there last offseason to the tune of a 4.46 ERA, though he got better as the season went on. His strikeout numbers and ratios fell in his first season in the American League, but the 29-year-old should benefit from a move to the pitcher friendly environment of Safeco Field.