Earlier this year we briefly utilized some heady chart porn to note that David Robertson had returned to using his curveball to make batters look silly. At the time, we characterized it as good news.  That appears to have been for good reason as Robertson’s hammer of doom has been extremely effective to date:

Batters are hitting a measly .091 against the curveball and have generated a wRC+ of  -6 (that’s NEGATIVE SIX) against the pitch this season. These are also the best marks Robertson has posted in each of these respective categories for his career. The reason underlying this success?  His overall contact rate on the pitch is only 48% this year which is well below his career average of 65%. Why? Batters are swinging through with aplomb. To date in 2013, opposing batters have a 23% swinging strike rate against the pitch; this is the highest swinging strike rate Robertson has ever induced on the pitch and it’s better than his career average for the pitch by 8%.

While Robertson has been criticized for his stumbles in the closer role last season, if he brings shutdown pitches like this to the table he more than deserves another shot at handling the ninth full time.