ST. PETERSBURG - APRIL 30: Relief pitcher Joakim Soria #48 of the Kansas City Royals pitches against the Tampa Bay Rays during the game at Tropicana Field on April 30, 2010 in St. Petersburg, Florida. (Photo by J. Meric/Getty Images)
Recently I ranted that I didn't like the saves category and that wish some other form of system was used. Tom Tango took this as a challenge and solicited some help over at his blog. So far they have come up with using WPA (Win Probability Added) as the data to measure the releiver and set cutoff values at +/- 0.05 WPA for each reliever appearance.
Win Probability measure the chance that a team will win a game and is probably most often seen in the game graphs at Fangraphs. The value 0.05 is the equivalent to a 5% change for the team winning. The categories don't have official names yet, but I like the names Shutdowns and Meltdowns that have been mentioned. Here is a look at how the Royals pen has done so far this year (excludes last night).
No real surprises. Hopefully the shutdowns will start over taking the meltdowns soon.
Let me know your thoughts on this format on evaluating relievers.