Tuesday, July 01, 2008

Mid-season FIP update

Today, I'll continue my mid-season analysis of the Tigers looking at Fielding Independent Pitching (FIP or FIP ERA). FIP is a measure of how well a pitcher performs in events which he can control without the influence of fielders - home runs, strikeouts, walks and hit batsmen. The formula is

(HR*13+(BB+HBP)*3-K*2)/IP, plus a league-specific factor added to make it equivalent to a real ERA.

While real ERA is affected by fielding, FIP gives you an idea of how well a pitcher performed regardless of how much fielding support he received. FIP was invented by Tangotiger.

Table 1 below indicates how Tigers starters rank among 48 American League starters with 80 or more innings pitched so far this year. The data were extracted from the Hardball Times site. The columns of the table are described below:

ERA = actual ERA.

FIP = Fielding Independent Pitching ERA

DER = the Defensive Efficiency Ratio (proportion of balls in play converted into outs) of the team when the given pitcher is on the mound.

FIP-ERA = FIP minus ERA.

LOB% = percentage of runners put on base which have been left stranded.

The table shows that none of the Tigers are in the top half of the league in FIP. Justin Verlander (4.09) and Nate Robertson (4.11) lead the Tigers and are ranked 27th and 28th respectively. Since FIP tends to be a decent indicator (more so than ERA) of future success, this would normally be a bad sign for the second half. The good news is that most of the damage was done early and they are pitching a lot better now.

Armando Galarraga's FIP (4.39) is about a run higher than his ERA (3.40) which suggests that he is probably not pitching as well as his ERA indicates. The component which drags down his FIP is his 3.3 walks per game which is in the bottom ten in the league. One factor which is likely helping his ERA is his .774 DER (third in the league). This indicates that he may be benefitting from some combination of above average fielding support and luck. I would expect his actual second half ERA to be closer to 4.39 than 3.40.

In contrast to Galarraga, Robetson's FIP (4.11) is more than a run lower than his actual ERA (5.23). Despite his third worst in the AL ERA, Robertson has a good BB/ 9 IP ratio (2.5) and a respectable K/ 9 IP ratio (6.0). Unlike The Big Cat, Nate has a very low .661 DER (third worst in the AL) so he may be getting poor fielding support or perhaps has been unlucky.

In conclusion, the Tiger starters have done well so far this year even if they have improved substantially since mid-May. In the second half, we can probably expect Robertson's ERA to improve and Galarraga's ERA to regress based on their ERA/FIP differentials. I would also expect Verlander and Rogers to have better ERAs in the second half simply because they are pitching better now than they were in the first half of the season.


Table 1: FIP for Tigers starters (through June 30, 2008)

Rank

Pitcher

IP

ERA

FIP

DER

FIP-ERA

LOB%

27

Verlander

108

4.42

4.09

.729

-0.33

67.2

28

Robertson

96 1/3

5.23

4.11

.661

-1.12

69.4

36

Galarraga

82

3.40

4.39

.774

0.99

69.4

43

Rogers

100

4.59

4.90

.702

0.31

70.8

---

Bonderman

71 1/3

4.29

4.98

.709

0.69

74.0

5 comments:

  1. Lee, how much does line drive rate correlate with pitchers and their BABIP> I ask because as of the last time I checked, Robertson's was higher and he appeared to be giving up a lot more extra base hits. As such, I'm not expecting his ERA to come back down anytime soon.

    ReplyDelete
  2. Eddie,

    That's an interesting question. I'd like to know how many extra base hits he has given up. There is a significant correlation between line drive rate and BABIP. However, pitchers have less control over whether batted balls become line dives than hitters do. So, I don't know whether he'll keep on giving up line drives.

    Looking at Robertson's line drive rate, he ranks about 30th out of 48 pitchers so it's not ridiculously high. His HR/FB is pretty high though. it's something else to watch.

    Lee

    ReplyDelete
  3. Doubles+Triples allowed:

    Robertson: 33
    Rogers: 30
    Verlander: 18
    Galarraga: 16

    I'd be more inclined to think that a pitcher has more control over doubles and triples than singles... but that's just a hunch.

    ReplyDelete
  4. Thanks for the data Eddie. Doubles and triples allowed by pitchers is something I have not studied much. It might be a good project for the winter. I'd like to find out whether extra base hits allowed by pitchers is a repeatable event and how much it affects the discrepancy between FIP and ERA.

    Lee

    ReplyDelete
  5. I went through and started doing it, but there was too much noise. For one, I was only counting pitchers who faced at least 500 batters in a season. For the 8 pitchers on the Tigers in 2006 and 2007, I got an R^2 of about .65 between (2B+3B)/PA and ERA-FIP.

    Once I brought in the Tigers' 2005 and 2004 pitchers, that went way down, into the .3-.4 range. I'm suspecting that is because the defense was so much better in 2006-2007 than in 2004-2005.

    ReplyDelete

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