Wednesday, May 15, 2013

Anibal Sanchez Among Early Pitching Leaders

Today, I'll take my first look at some of my favorite sabermetrics pitching leaders.  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 has 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. 

It is not known exactly how much control pitchers have on the results of balls in play, but recent research tells us that some pitchers are better than others at preventing hits on balls in play.  For example, Mike Fast, formerly of Baseball Prospectus and now a MLB sabermetrician, used Sportsvision's hit f/x data to show how pitchers varied on the speed of balls off the bat.

So, rather than making the big leap from ERA to FIP, it might be a good idea meet 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.  Hishashi Iwakuma of the Mariners currently leads the league with a .208 wOBAA.  The top Tiger is Anibal Sanchez, sixth in the AL at .251. Max Scherzer was 11th prior at .267 prior to today, but likely dropped down the list quite a bit with today's performance.  Justin Verlander (.267) and  Doug Fister  (.287) are 12th and 18th respectively.

Table 1: AL wOBA Against Leaders

Player
Team
G
IP
wOBAA
Hisashi Iwakuma
SEA
8
51.2
.208
Yu Darvish
TEX
8
52.2
.240
Clay Buchholz
BOS
8
58.2
.244
Felix Hernandez
SEA
9
64.2
.246
James Shields
KCR
8
58.0
.247
Anibal Sanchez
DET
8
52.2
.251
Jon Lester*
BOS
8
52.2
.252
Chris Sale*
CHW
8
56.1
.258
Hiroki Kuroda
NYY
8
50.2
.259
Derek Holland*
TEX
8
55.1
.261
Max Scherzer
DET
7
47.1
.267
Justin Verlander
DET
8
51.1
.268
Matt Moore*
TBR
8
48.0
.275
Justin Masterson
CLE
9
63.0
.277
Ervin Santana
KCR
7
48.1
.284
Jake Peavy
CHW
7
45.2
.285
Doug Fister
DET
8
50.0
.287
Zach McAllister
CLE
7
43.2
.291
Wei-Yin Chen*
BAL
8
47.1
.292
A.J. Griffin
OAK
8
51.2
.300

Data source: Baseball-Reference

It's generally a good thing to convert to runs allowed when trying to evaluate pitchers, so I'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.

Sanchez has 16 Base Runs Against in 52 2/3 innings so far this year.  This means that he should have allowed an estimated 16 runs based on the number of base runners, total bases and home runs he has allowed.  He has allowed 14 actual runs, so runs are scoring against him at a slightly lower rate than you would expect so far.  That could possibly be due to good defense, unfortunate timing or just bad luck on locations of batted balls.

Sanchez has 10 Base Runs Above Average (RAA) which means that he has saved the Tigers an estimated 10 runs compared to the average pitcher in the same number of innings.  Table 2 shows that he is ninth in the league on that metric.  Iwakuma is the league leader at 14.   Other Tigers among the leaders include Verlander and Fister, both with 8.      

Table 2: AL Runs Saved Leaders

Player
Team
G
IP
Base Runs
RAA
Hisashi Iwakuma
SEA
8
51.2
11
14
Clay Buchholz
BOS
8
58.2
15
13
Felix Hernandez
SEA
9
64.2
18
13
James Shields
KCR
8
58.0
16
13
Yu Darvish
TEX
8
52.2
14
11
Chris Sale*
CHW
8
56.1
17
10
Justin Masterson
CLE
9
63.0
21
10
Jon Lester*
BOS
8
52.2
15
10
Anibal Sanchez
DET
8
52.2
16
10
Derek Holland*
TEX
8
55.1
18
9
Hiroki Kuroda
NYY
8
50.2
15
9
Justin Verlander
DET
8
51.1
17
8
Doug Fister
DET
8
50.0
17
8
Max Scherzer
DET
7
47.1
16
7
Wei-Yin Chen*
BAL
8
47.1
18
5
Data source: Baseball-Reference 

Finally, Table 3 shows that Sanchez has allowed 2.69 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.  Patriot 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, Sanchez has a 2.50 WERC which places him seventh in the league. Once again, Iwakuma (1.85) is the AL leader.

Table 3: AL WERC Leaders


Player
Team
G
IP
Base Runs/9 IP
WERC
Hisashi Iwakuma
SEA
8
51.2
1.99
1.85
Clay Buchholz
BOS
8
58.2
2.33
2.17
James Shields
KCR
8
58.0
2.42
2.25
Yu Darvish
TEX
8
52.2
2.43
2.26
Felix Hernandez
SEA
9
64.2
2.55
2.37
Jon Lester*
BOS
8
52.2
2.65
2.47
Anibal Sanchez
DET
8
52.2
2.69
2.50
Chris Sale*
CHW
8
56.1
2.72
2.53
Hiroki Kuroda
NYY
8
50.2
2.76
2.57
Derek Holland*
TEX
8
55.1
2.89
2.69
Justin Masterson
CLE
9
63.0
2.93
2.73
Justin Verlander
DET
8
51.1
2.96
2.75
Max Scherzer
DET
7
47.1
2.96
2.76
Doug Fister
DET
8
50.0
3.03
2.82
Wei-Yin Chen*
BAL
8
47.1
3.35
3.12

 Data source: Baseball-Reference

Some may have noticed that the Tigers rank lower on WERC than FIP which had their big four starters - Sanchez, Verlander, Scherzer and Fister - all in the top eight entering today.  The FIP metric, of course does not involve hits allowed.  The Tigers starters have been allowing a lot of hits on balls in play as all four have BABIPs of .312 or greater.  You could blame this on poor fielding or bad luck, but we don't know to what extent that's true.  Therefore, it's useful to see where they stand if hits are taken into account.  

I would guess that the Tigers FIPs and WERCs will move closer together as the season progresses.  I'll update these numbers again when we have a larger sample size.

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