Sunday, September 08, 2013

Scherzer, Sanchez Lead AL in Run Prevention

In a recent post, I evaluated a pitcher's run prevention based only on runs allowed (RA) and innings pitched (IP).  To this end, I used the Pitching Runs metric which is calculated as

     Pitching Runs = IP * Lg RA / 9 - R

The current American League Pitching Runs leaders are shown in Table 1 below.  Tigers ace Max Scherzer has taken over the lead with 28.1 Pitching Runs.  This suggests that he has saved the Tigers about 28 runs above an average pitcher in the same innings.  This is above average, not above replacement.  An example of an average pitcher would be Jeremy Guthrie of the Royals.  Scherzer is followed by Rangers right hander Yu Darvish (26.8) and fellow Tigers Anibal Sanchez (26.6).

Table 1: AL Pitching Runs Leaders

Player
Team
IP
Pitching Runs
Max Scherzer
DET
190.1
28.1
Yu Darvish
TEX
179.2
26.8
Anibal Sanchez
DET
158.1
26.6
Hisashi Iwakuma
SEA
196.2
26.1
Felix Hernandez
SEA
194.1
24.0
Bartolo Colon
OAK
164.1
22.5
Hiroki Kuroda
NYY
177.2
21.9
Chris Sale*
CHW
187.2
20.7
James Shields
KCR
199.2
18.5
Justin Masterson
CLE
189.1
16.6
Derek Holland*
TEX
190.1
14.1
Jered Weaver
LAA
135.1
13.5
Ervin Santana
KCR
184.0
13.2
Matt Moore*
TBR
126.2
13.1
Chris Tillman
BAL
172.1
11.4


The Pitching Runs metric is appealing because it is simple to understand and calculate, but it does not consider factors such as home ballpark and fielding support.  We can calculate runs due to ballpark for Scherzer as follows:
  • The average AL pitcher allows 4.32 runs per game or 0.48 runs per inning.  In 190 innings (Scherzer's total), this pitcher would allow 190 * .48 = 91.2.
  • A pitcher pitching his home games at Comerica Park inflates his Run Average by 2% on average.  So, the Park Factor (PF) is 1.02.
  • The average pitcher would allow .48*1.02 = .4896 runs per inning pitching in Comerica Park half the time.  That comes out to 93.0 in 190 innings.
  • The difference between 91.2-93.0 yields -1.8 Ballpark Runs.  In other words, Scherzer has theoretically allowed 1.8 extra runs due to pitching in Comerica.
The number of runs due to fielding can be estimated by one of many team fielding metrics.  We could use a zone-based play-by-play measure such as Defensive Runs Saved (DRS) or an aggregate measure such as Total Zone).  If you don't trust fielding metrics at all, you could also punt fielding and assume that all teams give average support to their pitchers.  I have chosen to take the average of these three.

The Tigers, have a DRS of -40 which means their fielders have allowed an estimated 40 runs more than what you would expect from an average fielding team.  Their Total Zone of -61 is interpreted similarly.  The average of -40, -61 and 0 is 33.7 Team Fielding Runs.  Fielding Runs for individual pitchers can be calculated as follows:
  • There have been 3,596 balls in play against the Tigers pitching staff.  Scherzer has had 463 balls in play in his starts. That is 12.88% of the team's ball in play.
  • Multiplying .1288 by -33.7 Team Fielding Runs yields -4.4 Fielding Runs (Yes, it's a big stretch to assume that all of a staff's pitchers get the same level of support from their fielders, but it's the best that can be done given the available data)..
Finally, Adjusted Pitching Runs is calculated by subtracting Ballpark Runs and Fielding Runs from Pitching Runs.  For Scherzer, that is 28.1 - (-1.8) - (-4.4) = 34.3 Adjusted Pitching Runs.  So, after considering ballpark and fielding, Scherzer is an estimated 34.3 runs better than an average pitcher in the same number of innings.

The Adjusted Pitching Runs Leaders are shown in Table 2 below.  You will note that Scherzer and Sanchez (32.1) are the top two pitchers in the league on this metric.  Not only that, but Doug Fister (14.9) and Justin Verlander (12.2) are also in the top 15.

So, that's more support for Scherzer's Cy Young worthiness and more evidence that the Tigers have best staff in the league.

Table 2: AL Adjusted Pitching Runs Leaders

Player
Team
IP
Pitching Runs
Ballpark Runs
Fielding Runs
Adjusted Pitching Runs
Max Scherzer
DET
190.1
28.1
-1.8
-4.4
34.3
Anibal Sanchez
DET
158.1
26.6
-1.5
-4.0
32.1
Chris Sale*
CHW
187.2
20.7
-4.5
-5.0
30.2
Hisashi Iwakuma
SEA
196.2
26.1
2.9
-6.8
30.0
Yu Darvish
TEX
179.2
26.8
-6.1
3.4
29.5
Felix Hernandez
SEA
194.1
24.0
2.8
-6.4
27.6
Hiroki Kuroda
NYY
177.2
21.9
-2.6
-1.1
25.6
Bartolo Colon
OAK
164.1
22.5
1.6
-2.2
23.1
Jose Quintana*
CHW
172.2
7.4
-4.2
-5.2
16.8
Jered Weaver
LAA
135.1
13.5
0.0
-2.6
16.0
Justin Masterson
CLE
189.1
16.6
2.7
-1.8
15.7
Derek Holland*
TEX
190.1
14.1
-6.4
4.8
15.7
Doug Fister
DET
179.2
7.8
-1.7
-5.3
14.9
John Lackey
BOS
168.0
10.4
-4.1
0.4
14.1
Justin Verlander
DET
192.2
5.1
-1.9
-5.2
12.2
 Data source: Baseball-Reference.com

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