Saturday, November 12, 2011

Verlander, Fister Rank High on Base Runs Statistic

In previous posts, I used Pitching Runs Saved (PRS) to evaluate pitchers.  To review, PRS is designed to isolate pitching performance from fielding support and ballpark factors.  It is calculated by substracting ballpark runs (BPR) and fielding runs saved (FRS) from runs allowed above average (RAA).  Tigers ace Justin Verlander had 60.8 PRS in 2011 which means that he saved the Tigers an estimated 61 runs over an average starter in the same number of innings pitched.  

There are a few limitations of PRS.  First, the fielding component is uncertain as we still can't measure fielding as precisely as we can measure hitting.  Thus, one might wish to remove FRS and just take the sum of RAA and BPR.  However, that leaves us with no estimation of how many runs allowed were due to pitching versus fielding.  Still it's better than a statistic such as ERA which does not give a pitcher credit for his innings pitched.    

Even if you trust the fielding component of the PRS calculation, another issue is that a pitcher has no control over what happens after he leaves the game   If he departs with a man on first with two outs and the relief pitcher allows a run-scoring double, the starting pitcher is charged with the run. In other words, a pitcher’s ERA is dependent not only on the quality of his innings but also on the quality of the innings of his relievers.

Another potential concern regarding ERA is the timing of hits, walks and extra base hits. For
example, if a pitcher pitches nine innings and gives up nine hits with each hit coming in a
different inning, he will almost surely allow fewer runs than if he surrenders all the hits in one
inning. If a pitcher frequently allows a lot of baserunners and extra base hits, he might get away with a relatively low ERA one year but it wouldn't necessarily be based on skill.

A related issue to the distribution of baserunners is sequencing of events. Let’s say a pitcher
allows the following sequence of events in an inning:

1. Ground out
2. Single
3. Single
4. Homer
5. Strikeout
6. Fly out

In this case, he would be charged with three runs allowed for the inning. Now, suppose that
Pitcher B has a slightly different sequence of events in another inning:

1. Ground out
2. Homer
3. Single
4. Single
5. Strikeout
6. Fly out

In this case, the pitcher is charged with one run. Both pitchers surrendered a homer and two
singles but Pitcher B allowed two fewer runs just because the sequence of hits was different.

While pitchers vary in their ability to prevent baserunners from scoring, research by Ron Shandler – author of The Baseball Forecaster and publisher of BaseballHQ.com
– suggests that this has more to do with overall pitcher quality than clutch pitching ability. In
other words, most pitchers who consistently strand runners do so primarily because they get
strikeouts and limit base runners in all situations, not because they have a lot of control over
clustering of base runners or sequencing of events.  In other words, much of the bunching and sequencing seems to based on luck to some extent. 

In order to remove, clustering of base runners and sequencing of events from the equation, we can used a component-based statistic.  One such measure is the Base Runs statistic created by David Smythe in the early 1990s.  It is based on the idea that we can estimate team runs scored if we know the number of base runners, total bases, home runs and the typical score rate (the score rate is the percentage of base runners that score on average).  Base Runs also works well for individual pitchers.  The complete formula can be found here.

Verlander had 71.8 Base Runs Allowed in 2011.  This means than a pitcher with his innings, base runners, total bases and home runs allowed would typically allow about 72 runs.  In actuality, he allowed 73 runs, so his run total was not affected too much by unusual hit bunching or sequencing of events.

An average Comerica Park pitcher would be expected to allow 130.2 runs.  So, Verlander was 130.2 - 71.8 = 58.4 Base Runs Saved Above Average (BsRAA).  The table below shows that he was the run-away leader in the American League.  Angels right-hander Jered Weaver (43.1)  was a distant second about 15 BsRAA behind.

Another familiar starter Doug Fister ranked sixth with 37.1 BsRAA: 17.6 with Seattle and 19.5 with Detroit.  The tall slim right-hander also ranked fifth in the league with 33.6 PRS.  Yes, he was really good last year.

Table 1: American League Base Runs Saved Above Average Leaders, 2011


Player
Team
IP
Base Runs
BsRAA
Justin Verlander
DET
251.0
71.8
58.4
Jered Weaver
LAA
235.2
75.3
43.1
Josh Beckett
BOS
193.0
63.0
40.5
James Shields
TBR
249.1
84.9
37.4
Dan Haren
LAA
238.1
82.5
37.3
Doug Fister
SEA/DET
216.1
71.3
37.1
C.J. Wilson*
TEX
223.1
83.5
36.0
CC Sabathia*
NYY
237.1
93.2
31.7
Ricky Romero*
TOR
225.0
86.9
28.2
Alexi Ogando
TEX
169.0
63.9
26.6

Note: Some of the statistics for this post were abstracted from Baseball-Reference.com

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