Alex Conway, of Orioles Nation, writing about the recently acquired Grant Balfour:
One of my favorite advanced statistics to look at for relievers is WPA or Win Probability Added. It measures the players effectiveness in so called high leverage situations. For instance, if a pitcher records an out with the bases loaded in the bottom of the 9th with only a one run lead, a positive WPA score is given to the player. Conversely, if they give up a run in the same situation the player gets a negative WPA score. I believe WPA is best used for relievers because in my mind, relievers exist to get outs in high leverage situations, if they don’t do that, then they aren’t very good relievers. Balfour has, over the past two years of closing, posted a WPA of 2.44 in 2012 and 2.56 in 2013. He had the 15th best WPA for qualified relievers in baseball for the 2013 season.
This certainly is in line with Balfour's on field persona and the noted confidence he brings to every game.
However, this acquisition, much like the Jim Johnson trade, does not exist in a vacuum. Balfour is Johnson’s replacement. Why I liked the Johnson deal when it was made is because of acquisitions like this. Dan Duquette turned Jim Johnson and his likely $10 million salary into Grant Balfour, Ryan Webb (you can read my analysis on Ryan Webb here), Jemile Weeks, and David Freitas. That’s two solid relievers, a starting 2B candidate, and some minor league catching depth for the same amount of money the Orioles would have paid Jim Johnson. I cannot say whether Johnson or Balfour will perform better next year, but they are essentially on the same plane of great, but not elite, closers.
Paul recently talked about how we needed to wait and see how the off-season progressed to see if the Johnson trade would pay off economically. It certainly has off the field. We'll have to wait until the end of 2014 to see if it pays off on the field.