Shaffer was acquired by Seattle in a November deal with Tampa Bay along with utility man Taylor Motter in exchange for Minor Leaguers Andrew Kittredge, Dalton Kelly and Dylan Thompson.
Shaffer played in 51 games for the Rays over the past two seasons, posting a .213/.310/.410 line with five home runs and 10 RBIs in 142 plate appearances. The 6-foot-3, 220-pounder was the Rays' Minor League Player of the Year in 2015 after hitting 26 homers and 72 RBIs while splitting time between Double-A Montgomery and Triple-A Durham, including .