Hart, 32, is hitting .209/.295/.353 (85 OPS+) with five doubles, five homers and 17 RBI in 37 games this season, but he has potential to make a big impact on the offense. He's a two-time All-Star and hit .270/.334/.507 with 35 doubles and 30 homers in his last full season (2012 with Milwaukee).
Of course, Hart is a big injury risk. He missed all of the 2013 season following knee surgery and he's missed most of this season with hamstring issues and continued recovery from his surgery.
The Mariners enter Friday nine games over .500, holding the second wild-card spot and sitting five games behind the A's in the AL West.