Based on the way Brad Miller has played for the Tampa Bay Rays this season, it's likely that the Seattle Mariners regret letting him go. Last winter, Seattle sent Miller along with Logan Morrison and Danny Farquhar to Tampa Bay for Nate Karns, C.J. Riefenhauser (who is no longer in their system) and minor leaguer Boog Powell.
It's easy to say that now, of course, but at the time of the trade, Miller had just completed a season in which he slashed .258/.329/.402 and was worth only 0.