Thursday, August 23, 2012

Verlander is Good at wOBAA

It's been a little while since I have updated the sabermetrics pitching leaders, so I'll do that today while we savor the Tigers three-game sweep of the Blue Jays in a series dominated by pitching.  Most readers of this blog are aware of the limitations of ERA in evaluating pitcher performance.  Two of the biggest issues are:
  • ERA gives pitchers full credit/blame for results of batted balls in play despite the fact that they share that responsibility with fielders.  For example, a pitcher with a strong defense behind him will tend to give up fewer hits (and thus fewer runs) than if he had a poor defense behind him.
  • ERA gives pitchers full responsibility for sequencing or timing of events, that is, it assumes that they can control when they give up hits and walks. For example, if a pitcher pitches extraordinarily well with runners in scoring position in a given year, he will have a lower ERA than if he had a typical year in those situations. Additionally, a pitcher who tends to bunch base runners together in single innings will have a higher ERA than if he had a typical year distributing base runners more evenly.
In reality, pitchers have limited control over both the number of batted balls that drop for hits and sequencing of events.  Thus, Defense Independent Pitching Statistics (DIPS) such as FIP, xFIP, tERA and SIERA have been developed to remove some of the noise of ERA.  DIPS are based on things that pitchers do control for the most part - walks, hit batsmen, strikeouts, home runs and types of batted balls (ground balls , fly balls, line drives, pop flies).

Because they are based on things that pitchers essentially control, the DIPS metrics are said to be better measures of true talent than ERA.  As a result, they are also better than ERA at predicting future performance. However, they only measure a portion of a pitcher's talent and should be used as complements to ERA rather than as replacements.

More and more fans are becoming comfortable with DIPS theory, but it is still a really difficult concept to get across to the mainstream.  If you ever try to explain FIP or any other DIPS statistic to the uninitiated, you will probably find that they are skeptical of a pitching statistic which ignores hits.  They are not likely to buy into it even if they realize the limitations of ERA. 

So, rather than asking fans to take the big leap from ERA to FIP, why not meet them half way?   Instead of removing hit prevention and sequencing in one step, it might be better to remove one factor at a time.  Bill James did that with his Component ERA (ERC).  Applying the runs created methodology to pitchers, he determined what a pitcher's ERA should have been based on walks, hit batsmen,  strikeouts, homers AND hits allowed.  I'm going to look at some similar statistics here based on more modern measures such as linear weights and Base Runs. 

We often use Weighted On-Base Average (wOBA) to measure overall hitting performance and it can also be used for pitchers.  The American League wOBA Against (wOBAA) leaders are shown in Table 1 below.  Tigers ace Justin Verlander currently leads the league with a .263 wOBAA.  Following Verlander are Jered Weaver of the Angels (.264), Rays southpaw David Price (.271), Mariners fire baller Felix Hernandez (.271) and White Sox youngster Chris Sale (.275).  These same five pitchers will show up on the top of all the leaderboards in this post. 

Oft-injured starter Doug Fister is 18th in the league at .315.  So, if he is out for an extended period of time with his groin injury, it could hurt the Tigers a lot. 

Table 1: AL wOBA Against Leaders

Player
Team
G
IP
wOBAA
Justin Verlander
DET
25
181.2
.263
Jered Weaver
LAA
23
148.0
.264
David Price*
TBR
25
170.0
.271
Felix Hernandez
SEA
26
187.2
.271
Chris Sale*
CHW
23
153.0
.275
Jason Hammel
BAL
18
109.1
.292
Jake Peavy
CHW
24
168.0
.294
Jarrod Parker
OAK
21
129.1
.298
Hiroki Kuroda
NYY
25
167.0
.300
Bartolo Colon
OAK
24
152.1
.305
C.J. Wilson*
LAA
26
159.1
.306
Jason Vargas*
SEA
26
176.0
.306
Jose Quintana*
CHW
17
104.1
.306
CC Sabathia*
NYY
20
141.2
.307
Tommy Milone*
OAK
24
153.1
.310
Colby Lewis
TEX
16
105.0
.314
Scott Diamond*
MIN
19
128.0
.314
Doug Fister
DET
19
117.2
.315
Matt Harrison*
TEX
24
161.0
.315
Matt Moore*
TBR
24
143.2
.316
 Data source: Baseball-Reference

It's generally a good to convert to runs allowed when trying to evaluate pitchers, so we'll do that next.  The Base Runs measure was 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 has 56 Base Runs Against in 181 2/3 innings so far this year.  This means that he should have allowed an estimated 56 runs based on the number of base runners, total bases and home runs he has allowed.  He has allowed 61 actual runs, so runs are scoring against him at a higher rate than you would expect so far.  That could possibly be due to bad defense, unfortunate timing or just bad luck on locations of batted balls.  The fact that 10 of the runs against him are unearned points towards his fielders. 

Verlander has 33 Base Runs Above Average (RAA) which means that he has saved the Tigers an estimated 33 runs compared to the average pitcher in the same number of innings.  Table 2 shows that he is second in the league behind Hernandez (37) on that metric.  Fister is 20th with 5 RAA.  


 Table 2: AL Runs Above Average Leaders

Player
Team
G
IP
Base Runs
RAA
Felix Hernandez
SEA
26
187.2
55
37
Justin Verlander
DET
25
181.2
56
33
David Price*
TBR
25
170.0
52
32
Jered Weaver
LAA
23
148.0
45
28
Chris Sale*
CHW
23
153.0
51
25
Jake Peavy
CHW
24
168.0
61
22
Hiroki Kuroda
NYY
25
167.0
65
18
Jarrod Parker
OAK
21
129.1
49
15
C.J. Wilson*
LAA
26
159.1
64
15
Jason Vargas*
SEA
26
176.0
74
13
Jason Hammel
BAL
18
109.1
42
12
Jose Quintana*
CHW
17
104.1
41
10
Matt Harrison*
TEX
24
161.0
70
10
Tommy Milone*
OAK
24
153.1
66
9
Scott Diamond*
MIN
19
128.0
55
9
Bartolo Colon
OAK
24
152.1
67
8
CC Sabathia*
NYY
20
141.2
62
8
Matt Moore*
TBR
24
143.2
64
6
Colby Lewis
TEX
16
105.0
46
6
Doug Fister
DET
19
117.2
53
5
  Data source: Baseball-Reference

Finally, Table 3 shows that Verlander has allowed 2.80 Base Runs per nine innings.  About 93% of runs are earned, so multiply this result by .93. to put it on the same scale as ERA. The final result is a weighted component ERA.  Although, I am not using linear weights here, I call it WERC because others have said they like the name. It's really not a novel idea though.  Toirtap of Walk Like a Saber has been using Base Runs to evaluate pitchers for a while but prefers to not convert to the ERA scale.

Getting back to the example, Verlander has a 2.60 WERC which places him fourth in the league behind Hernandez (2.46), Price (2.55) and Weaver (2.55).  Fister ranks 20th at 3.78.  I'll take a look at the rest of the Tigers pitchers in a later post.    

 Table 3: AL WERC Leaders

Player
Team
G
IP
Base Runs/9 IP
WERC
Felix Hernandez
SEA
26
187.2
2.65
2.46
David Price*
TBR
25
170.0
2.74
2.55
Jered Weaver
LAA
23
148.0
2.74
2.55
Justin Verlander
DET
25
181.2
2.80
2.60
Chris Sale*
CHW
23
153.0
3.00
2.79
Jake Peavy
CHW
24
168.0
3.29
3.06
Jarrod Parker
OAK
21
129.1
3.42
3.18
Jason Hammel
BAL
18
109.1
3.43
3.19
Hiroki Kuroda
NYY
25
167.0
3.50
3.26
Jose Quintana*
CHW
17
104.1
3.57
3.32
C.J. Wilson*
LAA
26
159.1
3.62
3.37
Jason Vargas*
SEA
26
176.0
3.80
3.53
Scott Diamond*
MIN
19
128.0
3.84
3.57
Tommy Milone*
OAK
24
153.1
3.90
3.63
Matt Harrison*
TEX
24
161.0
3.92
3.64
Colby Lewis
TEX
16
105.0
3.94
3.67
Bartolo Colon
OAK
24
152.1
3.95
3.67
CC Sabathia*
NYY
20
141.2
3.97
3.69
Matt Moore*
TBR
24
143.2
4.05
3.77
Doug Fister
DET
19
117.2
4.07
3.78
  Data source: Baseball-Reference

No comments:

Post a Comment

Sabermetrics Book

Sabermetrics Book
One of Baseball America's top ten books of 2010

Blog Archive

Subscribe

501 Baseball Books

501 Baseball Books
Recommended by Tiger Tales

Stat Counter

Site Meter