Wednesday, December 06, 2006

Team Run Prevention in 2006

Evaluation of the offensive part of the game is fairly straight forward. I’m going to get away from that for a while and go over to the defensive side. The goal of every baseball team when they are not at bat is to give up as few runs as possible. This, of course, is done with pitching and fielding. The problem is how to separate pitching from fielding so we can evaluate each one of them in isolation. Because pitching and fielding are so intertwined this is not an easy task. However, sabermetric advancements are being made.


The first person known to quantify team fielding ability in a useful way was Bill James in his abstracts published in the 1980s. He developed a measure which he called Defensive Efficiency Ratio (DER). DER is the percentage of times batted balls are turned into outs by the team's fielders, not including homeruns. There are different versions of the formula but the one now most commonly used is DER=(BFP-H-K-BB-HBP-0.6*E)/(BFP-HR-K-BB-HBP) where BFP = batters faced pitcher, H=hits allowed, K=strikeouts, BB=walks allowed, HBP=hits batsmen and E=errors.

For years, the only attempt to isolate pitching from fielding was ERA which was supposed to remove the effect of fielding errors from runs allowed. ERA is flawed, in part, because it is dependent on the whims of different official scorers. More importantly, it does not take into account the ability of fielders to get to balls.



In 2000, Voros McCracken 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 hit in the field of play. This conclusion was met with much skepticism even in the sabermetric community. His theory has been tested rigorously and weakened somewhat but his main concept has so far been shown to be true. That is, hits allowed by pitchers are more a function of team fielding ability than the ability of the pitcher.


The idea is that the contribution of pitching to overall team defense can be derived, for the most part, from walks allowed, strikeouts, homeruns allowed and hits batsmen issued. McCracken referred to those as Defense Independent Statistics (or DIPS). Tom Tango derived a statistic from DIPS called Fielding Independent Pitching (FIP) ERA. FIP ERA measures pitcher performance essentially independent from fielding. The formula is HR*13+(BB+HBP)*3-K*2)/IP plus a league specific factor to make it equivalent to ERA.



Looking at team statistics over the past 5 years, it is seen that 93% of the variance in team runs allowed per game (RA/G) is explained by FIP ERA and DER. This is a very high correlation and it supports the theory that FIP ERA and DER explain most of run prevention. Furthermore, FIP ERA, by itself, explains 64% of the variation in RA/G and that DER, by itself, explains 50% of the variation in RA/G. This tells us that pitching is more important to run prevention than fielding but that fielding is also essential. In short, what Bill James has always said is true: “Much of what we think of as pitching is actually fielding”.


So, we have DER to measure overall team fielding and FIP to measure overall team pitching. Table 1 below shows the runs allowed (RA), ERA, FIP and DER for each American League team in 2006. Table 2 shows how the teams rank on those statistics. The raw data were extracted from The Hardball Times site.


It can be seen from the tables that the Tigers gave up the fewest runs (4.17 per game) in the league and that they gave up 14% fewer runs than the league average (4.87 per game). They led the league in ERA (3.84) but finished third in FIP ERA (4.33). The fact that their FIP ERA was about a half run greater than their actual ERA indicates that their excellent pitching was backed by some strong fielding and that they may not have led the league in run prevention without the glove work.


They led the league with a .704 DER. I will note that DER is not purely a fielding stat because pitchers do have some control over batted ball types (line drives, ground balls, etc) and ballparks also play a role. However, it is a useful fielding measure and it’s also simple and accessible. In future articles, I will touch upon more sophisticated fielding stats which will further support the conclusion made here that the Tigers had a very strong fielding team in 2006.



Table 1: AL Team Run Prevention in 2006


Team

RA/G

ERA

FIP ERA

DER

Detroit

4.17

3.84

4.33

.704

Minnesota

4.22

3.95

4.04

.687

Oakland

4.49

4.21

4.43

.690

LA Angels

4.52

4.04

4.05

.693

Toronto

4.65

4.37

4.51

.696

NY Yankees

4.73

4.41

4.42

.697

Cleveland

4.83

4.41

4.36

.677

Texas

4.84

4.60

4.42

.681

Seattle

4.89

4.60

4.60

.692

Chicago Sox

4.90

4.61

4.56

.696

Boston

5.09

4.83

4.48

.682

Tampa Bay

5.28

4.96

4.82

.673

Baltimore

5.55

5.35

5.11

.681

Kansas City

5.99

5.65

5.28

.677

Average

4.87

4.56

4.53

.688

Table 2: AL Team Run Prevention Ranks in 2006


Team

RA/G Rank

ERA Rank

FIP ERA Rank

DER Rank

Detroit

1

1

3

1

Minnesota

2

2

1

8

Oakland

3

4

7

7

LA Angels

4

3

2

5

Toronto

5

5

9

3

NY Yankees

6

6

5

2

Cleveland

7

7

4

12

Texas

8

9

6

10

Seattle

9

8

11

6

Chicago Sox

10

10

10

4

Boston

11

11

8

9

Tampa Bay

12

12

12

14

Baltimore

13

13

13

11

Kansas City

14

14

14

13

2 comments:

  1. This is great information. I've been reading your site for a few weeks now and I just wanted you to know that it is appreicated. Thanks for the work you put into this.

    ReplyDelete
  2. Thanks so much for this information and the time you put into it, Lee. It makes this kind of analysis much more accessible and tangible.

    ReplyDelete

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