The Mariners have released Justin Miller according to Ryan Divish of The Tacoma News Tribune (on Twitter). Miller informed the team that he planned to exercise the May 1st opt-out clause in his contract, so they told him he could leave now.
The 33-year-old right-hander appeared in six games for Seattle's Triple-A affiliate this year, striking out seven and walking five in 8 2/3 relief innings. He last appeared in the big leagues with the Dodgers last season, when he posted impressive strikeout (11.1 K/9) and walk (3.0 BB/9) rates in 24 1/3 innings. Miller has also pitched for Giants, Marlins, and Blue Jays in an MLB career that started back in 2002.