Pitching on an Imbalanced Schedule

By John Coleman

2002

One of the by-products of repeated expansion, uneven leaguesizes and random inter-league play is the Imbalanced Schedule. Theschedule-maker now allots 76 intra-division contests for most teams inbaseball.

An NL Central team will face its NL Central foes 84 times,and the smaller AL West will spend 58 contests facing its three divisionalrivals.

Since we are all here to play a game of stats, (or in fact,live a life of stats) the question is not whether this imbalanced approachskews our stats, but by how much? And more importantly, can we somehow take astrategic advantage?

Do Yankee pitchers benefit from facing weak Baltimore andTampa Bay offenses twice as often as Oakland pitchers? Obviously they do, butto what degree, and what measurable effect does it have on their value?

I’ve assembled a chart of Opposing pitcher ERA’s for each MLteam, listed for the last 4 years.

Then, by grouping them according to division, we can seewhat kind of trouble each division has been cooking up for its opponentpitchers. The ERA figure is a measure of that team’s offense when facing otherteams from its own league.

Then I averaged each division and subtracted the overallleague figure from each total, which yields a positive or negative DivisionalERA Factor.

This factor behaves much as a Park Effect does. You onlynotice it when someone moves in or out of the context.

Here’s the AL Central:

AL	1998	1999	2000	2001
vs.Chi	4.82	4.41	5.57	4.59
vs.Cle	4.95	5.85	5.57	5.23
vs.Det	4.10	4.27	4.78	3.95
vs.KC	4.09	4.82	4.87	4.18
vs.Min	4.19	3.55	4.32	4.22
AL Central	4.43	4.57	5.02	4.44
	-0.23	-0.24	0.08	-0.04

Remember, these ERA’s belong to each team’s Offense, notpitching staff. Each figure is an aggregate of all AL pitchers facing that offense.The bottom line is the Divisional ERA Factor.

AL totals

4.66

4.82

4.93

4.48

The league totals are subtracted from the divisional totalsto come up with the Divisional ERA Factor. This figure means, essentially, thata pitcher facing the AL Central in 2001 would expect to lower his ERA by .04.

Here are Divisional ERA factors for all 6 divisions:

	1998	1999	2000	2001	3 year avg.	adjusted
AL Central	-0.23	-0.24	0.08	-0.04	-0.07	-0.03	76/162	47%
AL East	0.03	0.09	-0.32	-0.25	-0.16	-0.08	76/162	47%
AL West	0.25	0.19	0.30	0.38	0.29	0.10	58/162	36%
NL Central	0.19	-0.06	0.15	-0.02	0.02	0.01	84/162	52%
NL East	-0.23	-0.17	-0.40	-0.41	-0.33	-0.15	76/162	47%
NL West	-0.00	0.24	0.22	0.42	0.29	0.14	76/162	47%

For the sake of simplicity, I’ve taken a 3-year average andapplied a factor of the percent of divisional contests. The “adjusted” columnsuggests a recent historical norm for ERA effects between the divisions.

What is the meaning of all this?

I’m saying that a pitcher changing divisions from NL East toNL West can expect to have his ERA jump by an average of 29 points (before parkeffects) simply based on the increased level of offense he’ll be facing.

For example, Rick Reed left Shea Stadium for the Metrodome lastyear. His new stats were projected by removing Shea’s park effects, adding theNL to AL run increase, then accounting for The Metrodome’s park effects.

By using divisional effects, you’ll see that he also leftthe weakest offensive division for a nearly neutral context, which helpedfurther ruin his numbers for the Twins.

SO ANYWAY…

The big question is this: What does this have to do withfantasy baseball?

1) When a pitcher moves to a new division, expect him to feel theeffects of the offensive context. If El Duque moves to Texas, the new divisionalone will pop his ERA by a likely 18 points. The change in parks won’t helphim at all either!

2) Overall rotisserie value is unlikely to change by more than $3in even the most extreme cases, based on divisional factors. Park and teamfactors can be far more influential.

3) The “Draft starting pitchers in the weak divisions” strategywill not gain you any advantage, unless the starting pitcher is recentlyacquired. This is because a pitcher’s record and projections will always bebased on his performance within that weak division.

I’ll finish up by presenting my complete charts. In order touse this information effectively for projection, I advise modifying theAdjusted Divisional Effect from a 3-year average to a projected figure. I’llleave that job up to you! I’ll look forward to answering any of your questionsor abuse, presuming you’ve gotten this far!

AL	1998	1999	2000	2001
vs.Chi	4.82	4.41	5.57	4.59
vs.Cle	4.95	5.85	5.57	5.23
vs.Det	4.10	4.27	4.78	3.95
vs.KC	4.09	4.82	4.87	4.18
vs.Min	4.19	3.55	4.32	4.22
AL Central	4.43	4.57	5.02	4.44
	-0.23	-0.24	0.08	-0.04
Adjusted Divisional Effect Factor:					-0.03
AL	1998	1999	2000	2001
vs.Bal	4.82	4.68	4.50	3.91
vs.Bos	5.05	5.01	4.64	4.50
vs.NYA	5.51	5.29	5.01	4.73
vs.TB	3.42	4.41	4.04	3.67
vs.Tor	4.68	5.14	4.87	4.32
AL East	4.69	4.91	4.61	4.23
	0.03	0.09	-0.32	-0.25
Adjusted Divisional Effect Factor:					-0.08
AL	1998	1999	2000	2001
vs.Ana	4.45	4.13	4.96	3.95
vs.Oak	4.55	5.29	5.66	5.23
vs.Sea	5.14	4.96	5.38	5.20
vs.Tex	5.51	5.66	4.96	5.05
AL West	4.91	5.01	5.24	4.86
	0.25	0.19	0.30	0.38
Adjusted Divisional Effect Factor:					0.10
AL totals	4.66	4.82	4.93	4.48
NL	1998	1999	2000	2001
vs.Chi	4.75	4.24	4.19	4.40
vs.Cin	4.50	4.86	4.86	4.09
vs.Hou	4.70	4.55	5.59	4.76
vs.Mil	3.89	4.66	4.15	4.24
vs.Pit	3.64	4.08	4.50	3.62
vs.StL	4.80	4.45	5.13	4.76
NL Central	4.38	4.47	4.73	4.31
	0.19	-0.06	0.15	-0.02
Adjusted Divisional Effect Factor:					0.01
NL	1998	1999	2000	2001
vs.Atl	4.82	4.76	4.39	4.13
vs.Fla	3.78	3.56	3.92	4.02
vs.Mon	3.56	3.87	4.24	3.60
vs.NYN	3.93	4.98	4.45	3.60
vs.Phi	3.78	4.66	3.92	4.29
NL East	3.97	4.36	4.18	3.93
	-0.23	-0.17	-0.40	-0.41
Adjusted Divisional Effect Factor:					-0.15
NL	1998	1999	2000	2001
vs.Ari	3.58	5.17	4.60	4.86
vs.Col	4.70	5.22	5.22	5.32
vs.LA	3.68	4.40	4.55	4.34
vs.SD	4.09	4.19	4.19	4.45
vs.SF	4.90	4.86	5.44	4.81
NL West	4.19	4.77	4.80	4.76
	-0.00	0.24	0.22	0.42
Adjusted Divisional Effect Factor:					0.14
NL	4.20	4.53	4.58	4.33

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