Defending the Indefensible: Theo Epstein & Unearned Runs

by Keith Scherer
August 12, 2004

Tiresome as discussion of the Nomar Garciaparra trade has become, one aspect of the criticism surrounding the trade deserves another moment’s attention: whether Boston’s gaudy unearned runs should have been a significant reason to make the deal.

At no point during his press conference did Theo Epstein mention unearned runs, and I haven’t found any source that directly attributes such a comment to Epstein. So why is it an issue I want to discuss?

Because in his criticism of the trade, Baseball Prospectus columnist Joe Sheehan noted that focusing on unearned runs is “a sports-radio mentality that a major-league front office needs to be above.” The entirety of Sheehan’s criticism was in this mode: a series of insinuations that Epstein’s stated rationale for the trade was disingenuous, evidence of incompetence, or both.

For the sake of the argument, let’s assume that all those unearned runs were one of management’s many concerns. Derek Lowe and Bronson Arroyo, who both tend to give up a lot of ground balls, have suffered more than half of Boston’s unearned runs. At the time of the trade, the Red Sox were second to Arizona in unearned runs allowed.

Was it a hobgoblin of little minds? Or is it Baseball Prospectus that has it wrong?

Before I get into this, let me state up front that I am not out to defend the trade. My focus is specific: I want to address Sheehan’s remark about unearned runs.

Sheehan is alluding to a tenet of Baseball Prospectus, found in its Baseball Basics series and elsewhere on the site, that the concept of Earned Runs is so misleading that it needs to be abolished.

The argument against ERA is straightforward: the distinction between earned and unearned runs (UER) is a false dichotomy caused by a misperception. As Michael Wolverton puts it, “The main problem with unearned runs isn't errors, it's the notion that the pitcher's job ends whenever an error is made.”

ERA supposedly avoids charging a pitcher with runs that scored through no fault of his own. According to Baseball Prospectus, this metric has it backwards. ERA seeks to blame fielders for unearned runs, but unearned runs, like earned runs, are really caused by pitching failures and not by bad fielding. Wolverton is Baseball Prospectus’s chief exponent of the argument. He puts it this way:  

Errors will happen. Good pitchers will minimize the damage caused by them. That is, a good pitcher will allow fewer runners on base before the errors happen (so there aren't runners to score on the errors), and will allow fewer hits and walks after errors happen (so the runners who reached on errors won't score).

Therefore (so the argument goes), when measuring pitching success we ought to drop Earned Runs Allowed in favor of Runs Allowed.

It’s a reasonable argument. But it’s wrong.

We can test Michael’s conclusion, and Epstein’s supposed incompetence, with a simple study. For our sample we can take all major-league teams since 1990 (excluding strike-shortened 1994), and rank them in order of UER allowed. That’s a pool of well over 300 teams.

We can compare the top 20 percent (most UER) to the bottom 20 percent (fewest UER). If errors have very little to do with UER, then we should expect to see a small difference in the number of errors between these two groups. The spread of errors should be a lot smaller than the spread in the pitching categories. That’s not what we see.  

Category   Difference     
H              6%
BB             6%
HBP            4%
HR             4%
ER             9%
E             40%

Based on this study, it looks like fielding has plenty to do with UER.

This is not a tautology. It’s not just that there is an association between errors and UER (which of course is obvious); it’s that the relationship between them is much stronger than the relationship between UER and the “pitching failure” categories.

So how do we reconcile this with Wolverton’s conclusion that “there's little evidence that unearned runs have much to do with fielding, and there's plenty of evidence that they have a lot to do with pitching”? The problem was in his methodology.

As Tangotiger explains, “Where Wolverton went wrong was looking at the differential between earned runs and unearned runs. If he had divided runs by unearned runs he would have found that the typical pitcher gives up 10% of his total runs as unearned (from 1950 through 1990, anyway). So if Seaver has a 3.00 ERA, his UERA will be about 0.33. If Bob Knepper has a 4.00 ERA, his UERA will be 0.44.  It's the exact same rate, but it looks like Seaver is better at preventing UER.

“Just throw out ten names at random, and I'll bet that eight of them are within 2 percent of each other.”

I took him up on his challenge. I randomly selected ten names and came up with this:  

Pitcher          %UER
Tommy John        13 
Bob Friend        13
Bob Shaw          12
Charlie Lea       11
Randy Jones       11
Rick Reuschel     11
Dan Petry         11
Burt Hooton       10
Rich Dotson       10
Ron Guidry         8 

My random list shows seven of ten pitchers within 2 percent of each other. “That's pretty close to my guess,” Tango replies. “More importantly, Wolverton was saying how the leaders in UER were all good pitchers. In my list of UER/R, if you look at the extremes, I would be quite certain that those guys would NOT be great or bad pitchers, but a random group of pitchers. That is, the ERA of pitchers with a UER/R over 12 percent and under 8 percent would be roughly the same.”

The remarkable consistency of Tango’s findings, combined with the study I present above, makes it hard to argue that pitching is more responsible for unearned runs than fielding is. And if that’s true, then Boston’s league-leading total of UER wasn’t meaningless, and concern over it was not beneath the dignity of a major-league front office.

I need to take another second here and make clear what I am not arguing: I am not arguing that earned runs are all meaningful on the macro level. Run prevention is a team responsibility and runs, not earned runs, determine wins and losses. What I am arguing is that unearned runs can help us determine whether the defense is a problem.

Boston’s front office would have looked at more than errors to analyze its defense, but the errors would have been enough to tell them they had a serious problem. Did Red Sox management think all of this through? Of course they did.

Keith Scherer is an attorney with the Air Force JAG Corps. His email address is keithjscherer@cableone.net.