Baseball BeatFebruary 13, 2006
A Look at Unearned Runs by Pitcher Type
By Rich Lederer

I have thought for quite some time that groundball pitchers were more likely to experience defensive errors behind them for the simple reason that most fielding miscues occur on grounders rather than flyballs. As my high school baseball coach liked to say, "There are no bad hops in the air."

There are three primary reasons why groundballs lead to more errors than flyballs.

1. Groundballs are more difficult to field cleanly than flyballs.
2. Infielders are more likely to make throwing errors on groundballs than outfielders on flyballs.
3. Infielders are also held to a higher standard by scorekeepers than their counterparts.

With respect to point number three, when an infielder throws a ball low, high, or wide of the first baseman, he most likely will be charged with an error if the batter-runner is safe. On the other hand, if an outfielder throws a ball off line while attempting to nail a runner, he won't be charged with an error unless the ball gets away and the errant throw results in the runner advancing an extra base.

If my longheld belief is correct, groundball pitchers should give up more unearned runs than flyball pitchers. I decided to test my hypothesis to see if it is true by analyzing last year's data.

According to ESPN's stats, pitchers allowed 54,981 groundballs and 44,528 flyballs last year. The ratio of groundballs-to-flyballs was 1.23.

By the same token, pitchers allowed 19,760 runs and 18,202 earned runs. The ratio of runs to earned runs was 1.086. Conversely, the ratio of earned runs to runs was .921. In other words, .079 or 7.9% of the runs scored last year were unearned.


Graph courtesy of Dave Studeman, Baseball Graphs and The Hardball Times.

Derek Lowe led the major leagues in unearned runs as a percentage of total runs with .212. That's right, more than one out of every five runs Lowe allowed was unearned. Lowe's high number of unearned runs is partly a function of the number of groundballs he induces. A secondary cause could well be the Dodgers' infield defense, which The Hardball Times Baseball Annual rated as below average in 2005. There is also the potential for scorekeeper bias, as well as a certain amount of randomness, especially when dealing with smaller sample sizes.

Let's take a look at the top and bottom 20 pitchers in terms of allowing unearned runs as a percentage of total runs.


Pitcher          Team         %UER     G/F
Derek Lowe        LAD	   .212    2.92
A.J. Burnett      Fla	   .175    2.42
Jeff Suppan       StL	   .172    1.43
Mark Buehrle      CWS	   .172    1.40
Kevin Millwood    Cle	   .153    1.34
Josh Towers       Tor	   .149    1.23
Roger Clemens     Hou	   .137    1.41
Jason Marquis     StL	   .136    1.59
Scott Kazmir       TB	   .133    1.05
Nate Robertson    Det	   .133    1.59
Carlos Silva      Min	   .133    1.55
Jake Westbrook    Cle	   .132    3.13
Matt Morris       StL	   .129    1.60
Kenny Rogers      Tex	   .128    1.33
Do. Willis        Fla	   .127    1.40
Jamey Wright      Col	   .126    2.06
Br. Claussen      Cin	   .124    0.77
Cory Lidle        Phi	   .114    1.79
Bronson Arroyo    Bos	   .112    0.85
Kip Wells         Pit	   .112    1.29

The top 20 pitchers have a weighted-average G/F ratio of 1.51, or 22.8% higher than the league average (1.23). This would suggest that groundball pitchers are indeed more prone to giving up unearned runs than flyball types.


Pitcher          Team         %UER     G/F 
Joel Pineiro      Sea	   .000    1.29
Brian Lawrence     SD	   .009    1.46
Pedro Martinez    NYM	   .014    0.85
Ryan Franklin     Sea	   .018    0.95
Esteban Loaiza    Was	   .022    1.21
Kyle Lohse        Min	   .024    1.25
Jeff Francis      Col	   .025    1.00
Brad Penny        LAD	   .026    1.32
John Patterson    Was	   .028    0.61
Mark Redman       Pit	   .030    1.64
Aaron Harang      Cin	   .032    0.95
Horacio Ramirez   Atl	   .037    1.60
Johan Santana     Min	   .039    0.91
Freddy Garcia     CWS	   .039    1.60
Jamie Moyer       Sea	   .040    0.87
Brett Tomko        SF	   .040    0.95
David Wells       Bos	   .042    1.51
C.C. Sabathia     Cle	   .043    1.55
Jarrod Washburn   LAA	   .045    0.97
Jon Lieber        Phi	   .047    1.29

The bottom 20 pitchers in terms of allowing unearned runs as a percentage of total runs have a weighted-average G/F ratio of 1.15, or 6.5% below the league average. This data once again confirms that groundball pitchers are more apt to give up unearned runs than flyball types.

I could also present the data by listing the top and bottom 20 in G/F ratio and showing the percentage of unearned runs to total runs. However, for the sake of brevity, I have chosen not to run what amounts to a duplicate effort. Besides, batted ball types have been analyzed more than unearned runs/total runs. Ergo, I thought these lists would generate more new information than the other way around.

Everyone knows that Lowe is an extreme groundball pitcher. But how widely known is it that he also gives up more unearned runs than the average pitcher? Over the duration of Lowe's career, 13.2% of his runs allowed have been unearned vs. a league average of 7.9%.

What can we do with this knowledge? I'll be the first to recognize that I'm not trying to break any new ground here. Voros McCracken, who developed Defense Independent Pitching Stats (DIPS) five years ago; Tom Tippett and Mitchel Lichtman have already beaten me to the punch.

David Gassko wrote an excellent article on Batted Balls and DIPS for The Hardball Times last August in which he concluded that "a pitcher's ground ball rate has a weak, but nonetheless significant, correlation with unearned runs allowed."

Gassko added:

The idea of earned runs, originally, was almost somewhat ingenious; it was the first attempt to separate pitching and fielding. But once we can characterize each outcome independent of defense, the need to separate earned and unearned runs disappears.

I would agree with David and recommend that we pay more attention to total runs than earned runs. Oh, you'll still find me giving an ERA here and there, but recognize that run average (RA) is an even better gauge of a pitcher's performance than earned run average.

Secondly, as it relates to ERA, be aware that a pitcher with a high percentage of unearned runs is more likely to regress than a pitcher with a low percentage of unearned runs. Not surprisingly, pitchers in the top 20 table above have a higher DIPS ERA relative to actual ERA than those in the bottom 20.

Lastly, do not make the mistake of discounting groundball pitchers. All else being equal, a groundballer is preferable to one who gives up flyballs. Yes, groundballs turn into more hits and errors than flyballs, but the latter are more harmful because they result in a greater number of extra base hits and home runs.

[Additional reader comments and retorts at Baseball Primer.]


What I notice is how good Seattle's infield defense must be...

What about strikeout rate and/or walk rate affecting unearned runs?

Couldn't see a clear correlation, but it seems more strikeouts = fewer chances for errors.

More walks = more runners = more chances for an error to lead to a run/extended inning/more batters/more error chances.

Perhaps DIPS and other such metrics account for this?

Infield defense may not matter as Lowe lead the league in unearned allowed, while Penny was 8th lowest. They had similar K/9 and BB/9.

Penny was more fly prone than Lowe, but still more groundballs than average.

Couldn't see a clear correlation, but it seems more strikeouts = fewer chances for errors.

Absolutely. More on this later.

The stats back up what Red Sox fans felt for a long time: the difference between Pedro Martinez and Derek Lowe was even greater than you'd think if you only looked at ERA.

Or...sure, ground ball pitchers are safer than fly ball pitchers (esp. at Fenway!) But strikeout pitchers are better more desirable than either of the other two.

Watching Willis and Burnett in particular last season mde me realise a couple of things others seem to overlook.

A lot of strikeouts in an outing can reduce its duration. AJ Burnett achieved relatively few strikeouts in his complete games, and indeed had no result the game in which he achieved his season's highest number (13), due partly to the fact he only went six innings.

He also seemed to give away more walks in the higher strikeout games.

Dontrelle Willis twice got as many as 7 strikeouts in his complete game victories, whilst his season high 12 came in a no result 7 inning performance and the next best 10 was over a 7 inning win. I think in the case of Dontrelle Willis, the games he got a lot of strike outs were not so much the games he had his best stuff, but the ones where he got into jams and had to freeze base runners.

Willis pitched an average of 7.5 innings in his victories and 5.2 innings when defeated. It gets a bit strange when you realise that he threw an average of 105 pitches per victory and 102 pitches per defeat. He threw 113.5 in his no results.

Strike outs look good, and please the Fantasy types, but I would suggest there are pitchers out there who might do better if they pitched to contact and left the Ks to the small number of fireballers.