Andrew Miller – Boston Red Sox
Miller burst to national attention as a top pitching prospect as a starter, being one of the keys to the trade that sent Miguel Cabrera and Dontrelle Willis from the Florida Marlins to the Detroit Tigers. Instead of turning into that top of the rotation starter that he was expected to be, Miller flopped. Eventually, he was sent to the Boston Red Sox, who turned Miller into a reliever.
In the bullpen, Miller has thrived. Since the start of the 2012 season, he has produced a 6-9 record with a 2.88 ERA and a 1.175 WHiP. In 103 innings, Miller has struck out 152 batters against 47 walks. As good as Miller has been against lefties over his career, he has been a force this season. Lefties have only hit at a .149/.216/.234 batting line against Miller, striking out 25 times in 47 at bats.
If the Royals were to acquire Miller, he could be retained for the 2015 season as well. Miller is arbitration eligible for the third time after this season, making him more than a possible rental for a playoff chase.