Yeah, I know - baseball has more stats than any other sport, and I'm suggesting a new one. But the fact is, one of the current stats just isn't measuring what it's supposed to measure (at least not in all cases) and rather than looking at a meaningless number, I'd like to see it fixed.

The stat I'm referring to is Earned Run Average (ERA), defined as the average number of earned runs a pitcher gives up per nine innings. For a starting pitcher, this stat is fine. If someone pitches six innings and gives up two earned runs, we can safely assume he gives up roughly three runs per nine inning game (especially if he does this consistently throughout the year). My problem involves using the ERA for relief pitchers.

Take last night's Yankee game for example. In the fifth inning, Andy Pettitte gave up two infield singles and suffered an error by the first baseman, Doug Mientkiewicz, making it first and third with nobody out. Joe Torre lifted Pettitte for reliever, Scott Proctor. The score at the time was 4-2 in favor of the Yankees.

The runner on first immediately stole second, making it second and third. Proctor struck out the first batter he faced, then gave up a sacrifice fly (bringing a run home and advancing the runner on second to third), and then threw a wild pitch to bring a second run home. Score: 4-4. Then, Derek Jeter made another error, but the runner was caught stealing to end the inning.

At the end of this mess, Pettitte gets charged the two runs (although only one earned run due to the Mientkiewicz error) and Proctor is charged with no runs at all. Now, Pettitte deserves the two runs, because he put the runners on base, so the runs that scored are a result of his actions. No complaints there. But to charge Proctor with no runs is to assume that his job is merely to avoid making the problem worse. That's not the case. Proctor's job in this situation is to shut down the Devil Rays and maintain the Yankee lead, much like Pettitte would have been asked to do if they let him keep pitching. So, to call Proctor's performance "perfect" (i.e., no runs allowed) after giving up the lead strikes me as a mis-statement of what relief pitching is all about.

Relief pitchers are frequently brought into tight spots. The good ones get out of the jams without giving up any runs. The mediocre ones let a few runs in, and then stop the bleeding. The really bad ones start giving up runs of their own, but that's another topic for another day. My point is this: baseball's current stats judge the good relief pitchers and the mediocre relief pitchers as the same: no runs allowed. ERA = 0.00.

I suggest a new statistic called Earned Runs While Pitching (ERWP), to be defined as the average number of earned runs scored by the opposing team while a given pitcher is on the mound for nine innings. In the above situation, therefore, Pettitte would accrue one run toward his ERA in the fifth inning, but zero runs toward his ERWP (since no one scored while he was on the mound). Proctor would accrue zero runs toward his ERA, but two runs toward his ERWP.

If Pettitte and Proctor continue to have outings like they did last night all season long, Pettitte's ERA would rank him (deservedly) as a fairly mediocre pitcher, and Proctor's ERA would rank him tied for the best pitcher ever (ERA = 0.00). ERWP, on the other hand, would show Pettitte as better than average, and Proctor as having let the team down.

One could argue about which stat is most appropriate at what time (roughly: ERA for starting pitchers, ERWP for relievers), but at least we'd have both to consider.