BABIP is a stat becoming more and more accepted as a signal for pitchers whose WHIP and ERA are due for a fall or rise depending on an unusually low or high BABIP. This appears most applicable to starting pitchers due to the large number of innings pitched and opportunities for their BABIPs to correct to the .300 level.
What about relievers, and specifically closers? These pitchers throw an inning at a time and only in high pressure situations. Does this make a difference in BABIPs? I am not sure so I ran the BABIPs over the past five seasons for the current closers of each team. Granted, most closers do not remain so for five seasons, but I wanted as much data as possible to see if there is any trend - to the extent five seasons for a particular pitcher can be statistically significant.
If the BABIP stat is useful as a signal for potential trouble for a closer, does it necessarily mean that closer would lose his job? Mariano Rivera currently has a BABIP of .190. Will he lose his job if he gets hit around a bit? No. Texas Rangers' closer C.J. Wilson has a BABIP of .224. If he gets hit around a couple times, will he lose his job? Maybe.
How about the higher end? Is San Francisco Giants closer Brian Wilson as buy low candidate with a .356 BABIP or is he a candidate to lose his job because he isn't a good pitcher and has a higher BABIP because he gets hit harder than most?
The historical BABIPs are on the jump page.