Tracking reliever use a difficult endeavor

ESPN.com's Buster Olney has put together a series he calls the "Bullpen Management Index" in which he examines use -- and abuse -- of relievers by each major league team. For example, he leads off today's entry with the Atlanta Braves:

Only four National League teams have gotten more innings out of their rotation than the Braves, whose rotation is anchored by Derek Lowe, Javier Vazquez and Jair Jurrjens, and yet Atlanta has five relievers on pace to make 73 or more appearances, including Peter Moylan, who is on track for 87 appearances. Several Braves relievers are on pace to obliterate career highs in appearances and/or innings pitched, not a good sign.

But innings and appearances aren't all there is to it. Red Sox manager Terry Francona has talked quite a bit this season about the significance of warm-up pitches, of getting warm and sitting down and getting warm again, and how that can contribute as much to a reliever's fatigue as throwing 12 pitches in a game situation.

Baseball stats have come a long way over the last few years. We can predict future success far better using tools like BAPIP than we ever could just with batting averages and earned run averages.

But there's one final frontier no one yet has solved: Relief pitchers. No one yet has figured out how to solve the riddle that is the relief pitcher. Just look at the Tampa Bay Rays: A year ago, Grant Balfour (1.54 ERA), J.P. Howell (2.22 ERA) and Dan Wheeler (3.12 ERA) led a bullpen that played a huge role in getting the Rays to the World Series. So far this year, Howell has a 1.82 ERA but Wheeler (4.24 ERA) and Balfour (5.01 ERA) haven't been close to what they were a year ago.

Olney, by looking at appearances and innings pitched, certainly is going in the right direction: The more managers wear down their relievers, the worse they're going to pitch down the stretch. But, again, it's not just appearances.

Francona, in the Red Sox dugout, begins each game with a couple of charts taped to the wall. One chart represents his bullpen -- and it breaks down each pitcher by usage over the last week. If he threw 17 pitches in two-thirds of an inning the day before, the chart will say that. If he got up in the bullpen the day before, the chart will say that, too -- with an extra indication if he got up in the bullpen more than once.

Throwing and sitting and throwing and sitting can produce more wear and tear on a middle reliever's arm than pitching in a game. Francona makes an effort not to get guys up more than once; he usually doesn't warm up more than one pitcher at a time just because he doesn't want to waste bullets in the bullpen.

Olney, though, doesn't have bullpen stats. No one does. The Red Sox track usage of their own pitchers week to week and might even keep the stats for each guy over the course of the season, but no one has any sort of warmed-up-in-the-bullpen stat.

Until we can really measure how often each pitcher has to throw -- including whether or not a guy has to get up and throw two or three different times before coming into a game -- we're not going to be able to figure out which relievers have been used conservatively and which relievers are about to have their arms fall off.