Wednesday, December 03, 2008

FIP Analysis for Tigers Starters in 2008

I recently wrote an article for TigsTown where I used FIP to determine which minor league pitchers pitched better or worse than their ERAs. Today, I'll present the same analysis for their major league starters.

Although Earned Run Average has long been a standard measure of pitcher performance, it is limited by a couple of factors. First, earned runs are subject to the whims of different official scorers. More importantly, ERA does not take into account the ability of fielders to get to balls and this is a significant part of run prevention. A relatively new statistic – Fielding Independent Pitching ERA (FIP) –addresses the latter problem and is therefore a purer pitching performance metric than ERA.

In 2000, Voros McCracken, who later did statistical analysis for the Boston Red Sox, published the results of his study which showed that there is little difference among major league pitchers in their ability to prevent hits on balls put into the field of play. This conclusion was met with much skepticism, even in the sabermetric community but further analyses have shown that his theory is basically correct. That is, for most pitchers, hits allowed are more a function of fielders making plays than of the ability of the pitcher. In short, what Bill James has always said is true: “Much of what we think of as pitching is actually fielding”.

With McCracken’s discovery in mind, Tom Tango, author of The Book: Playing the Percentages in Baseball, created FIP from items which are independent of fielders: strikeouts, walks, home runs and hit batsmen. The formula for FIP is (HR x 13 + (BB+HBP) x 3 –K x 2)/IP plus a league specific factor to make it equivalent to ERA. That’s a complex calculation but you can just think of FIP as the ERA that a pitcher “should have had” based on his strikeout, walk, homer and hit batsmen rates. One of the benefits of FIP is that it is better than ERA at predicting future performance.

A comparison between ERA and FIP helps to identify pitchers that were lucky or unlucky during a particular season. A pitcher with an ERA that was a lot higher than his FIP was probably a little unlucky. It could mean that his fielders did not make a lot of good plays behind him or that he was the victim of a lot of cheap hits that found holes. Conversely, a pitcher with an ERA that was substantially lower than his FIP was probably somewhat lucky and may have received very good fielding support in his games.


Table 1 below displays the ERAs and FIPs for Tigers starting pitchers in 2008 (data abstracted from The Hardball Times). In this table, ERA is the pitcher’s actual ERA, FIP is the Fielding Independent Pitching ERA described above and FIP-ERA is the difference between FIP and actual ERA. The rank shows where each pitcher ranked among the 62 American League starters with 17 or more starts. Table 2 presents the American League FIP leaders.


Table 1: FIPs for Tigers starters in 2008.

FIP ERA Rank

Name

IP

ERA

FIP

DER

FIP-ERA

26

Verlander

201.0

4.84

4.16

.704

-0.68

47

Galarraga

178.7

3.73

4.95

.764

1.22

49

Robertson

168.7

6.35

4.97

.659

-1.38

57

Rogers

173.7

5.70

5.26

.682

-0.44

N/A

Miner

118.0

4.27

4.53

.719

0.26

N/A

Bonderman

71.3

4.29

5.19

.709

0.90



Table 1 shows that, while Armando Galarraga led Tigers starters in ERA, Justin Verlander had the best FIP (4.16). In fact, Galarraga's FIP (4.95) is close to Nate Robertson's FIP (4.97). Galarraga survived due to a very low .247 Batting average on Balls In Play (BABIP) and he's unlikely to sustain that next year. Thus, I would expect Galarraga to regress somewhat in 2009. I still think he'll be a decent starter but I wouldn't expect an ERA under 4.00 next year.

Verlander also had a FIP (4.16) which was far lower than his ERA (4.84). His 2008 FIP was actually better than his 2006 FIP (4.35). He should have a better ERA next year.


Robertson, on the other hand, did not pitch as poorly as his ERA indicated. Robertson will probably not repeat his .349 BABIP next year. I think we can expect ERA to be lower next year and it would have to be if he's going to stay in the rotation.

Jeremy Bonderman was another pitcher whose FIP (5.19) far exceeded his ERA (4.29). This is unusual as every other year of his career has been in the other direction with his ERA exceeding his FIP. Given his health issues, I'm not sure we can draw any conclusions from the change.

Table 2: American League FIP leaders in 2008

FIP ERA Rank

Name

Team

IP

ERA

FIP

DER

FIP-ERA

1

Lee

CLE

223.3

2.54

2.92

.699

0.38

2

Halladay

TOR

246.0

2.78

3.09

.716

0.31

3

Beckett

BOS

174.3

4.03

3.32

.685

-0.71

4

Santana

LAA

219.0

3.49

3.37

.711

-0.12

5

Mussina

NYA

200.3

3.37

3.37

.679

0.00

6

Sabathia

CLE

122.3

3.83

3.48

.689

-0.35

7

Burnett

TOR

221.3

4.07

3.52

.686

-0.55

8

Danks

CHA

195.0

3.32

3.52

.707

0.20

9

Greinke

KC

202.3

3.47

3.65

.692

0.18

10

Meche

KC

210.3

3.98

3.68

.697

-0.30

11

Lester

BOS

210.3

3.21

3.72

.703

0.51

12

Pettitte

NYA

204.0

4.54

3.74

.667

-0.80

13

Duchscherer

OAK

141.7

2.54

3.75

.765

1.21

14

Hernandez

SEA

200.7

3.45

3.80

.686

0.35

15

Vazquez

CHA

208.3

4.67

3.81

.684

-0.86

16

Baker

MIN

172.3

3.45

3.85

.716

0.40

17

McGowan

TOR

111.3

4.37

3.89

.685

-0.48

18

Shields

TB

215.0

3.56

3.92

.713

0.36

19

Weaver

LAA

176.7

4.33

3.93

.702

-0.40

20

Buehrle

CHA

218.7

3.79

3.98

.688

0.19

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