Ibanez likely took a look at the glut of left-handed hitters on the current Yankees' 40-man roster and decided he would get more playing time elsewhere. He's expected to share left field and DH duties for the Mariners, who lost 87 games last season. Seattle had already added Kendrys Morales via a trade with the Los Angeles Angels.
Ibanez played more than expected during the regular season due to injuries and came through with 19 home runs and 62 RBI in 384 at-bats But it was.Ibanez's late inning heroics in the stretch run and post-season that will not be forgotten. None more so than Game 3 of the division series with Baltimore when Ibanez, pinch-hitting for Alex Rodriguez, tied the game with a home run and then won it with another home run in the 12th inning.
All that being said the Yankees certainly did not need another 40+ year old player on the 2013 roster. Ibanez was a member of the Mariners from 1996-2000 and again from 2004-2008. He was a member of the NL pennant winning Philadelphia Phillies that lost to the Yankees in the 2009 World Series.