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