Kauffman Park Effects 2004

Since the season is over for the Royals I thought I'd update the Kauffman Stadium run scoring spreadsheet that I started before the season started and blogged about previously.

My interest in this began when considering how the fences being moved back 10 feet at the K last winter would affect the run scoring at the park. So here are the updated numbers:

	Home				Away			Index		

	Games	Royals	Opp	Opp%+	Games	Royals	Opp	Opp%+	Royals	Opp	Overall

2004	80	338	426	26%	82	382	479	25%	-9%	-9%	-9%

2003	80	433	512	18%	82	403	355	-12%	10%	48%	28%

2002	81	434	505	16%	81	303	386	27%	43%	31%	36%

2001	81	382	485	27%	81	347	373	7%	10%	30%	20%

2000	81	451	488	8%	81	428	442	3%	5%	10%	8%

1999	80	441	449	2%	81	415	472	14%	8%	-4%	2%

1998	80	353	492	39%	81	461	407	-12%	-22%	22%	-1%

1997	80	387	434	12%	81	360	386	7%	9%	14%	11%

1996	80	372	369	-1%	81	374	417	11%	1%	-10%	-5%

1995	72	285	346	21%	72	344	345	0%	-17%	0%	-8%

1994	59	325	287	-12%	58	249	245	-2%	28%	15%	22%

1993	81	370	354	-4%	81	305	340	11%	21%	4%	12%

1992	81	314	346	10%	81	296	331	12%	6%	5%	5%

1991	81	344	378	10%	81	383	344	-10%	-10%	10%	-1%

											

91-94	302	1353	1365	1%	301	1233	1260	2%	9%	8%	9%

95-03	715	3538	4080	15%	721	3435	3583	4%	4%	15%	9%

As you might have expected the end result is that fewer runs were scored at Kauffman Stadium this season than on the road to the tune of 9% - obviously a big difference from the trend of 2001-2003 when about 26% more runs were scored at the K and the historical trend of +9% since 1991. One shudders to think how many runs Darrell May and Brian Anderson might have given up with the fences at their 2003 distances. As it was they gave up 38 and 33 homeruns respectively, the former setting a Royals record.

However, these quick and dirty numbers don't translate directly into park factors used by sabermetricians to normalize statistics such as OPS and Runs Created. The calculation of BPF (Batter Park Factor) and PPF (Pitcher Park Factor) is rather complicated and a complete explanation can be found on baseball-reference.com using the same basic formula as Total Baseball and originally documented in The Hidden Game of Baseball.

Suffice it to say the BPF and PPF also take into account things like:

1) the innings pitched difference between home and road games (a good team at home will get fewer at bats and thus score fewer runs than on the road)
2) the impact of the team's park on the park factors of other teams
3) the fact that hitters don't get to bat against their own pitchers and vice versa
4) and that a player only plays half his games at his home park.

In addition they are typically calculated using averages over several seasons (I think it might make more sense to use weighted averages since I would assume that weather patterns varied by groups of years as well as single years). This is important since there is a large element of variation in run totals in a park from season to season based on weather, individual players, and simply luck. So I wouldn't be surprised if run scoring increased at the K next year since we had a cooler and wetter summer in KC than in years past.

So the BPF and PPF for these seasons from baseball-reference.com, which uses a 3 year average, actually calculate to:

Year  BPF PPF

2004  95   96

2003 113  112

2002 117  115

2001 110  109

2000 104  103

1999 101  101

1998 104  105

1997 102  103

1996  97   98

1995 103  103

1994 104  104

1993 104  105

1992 103  103

1991 100  101

Obviously this tends to even out the fluctuations between 1994-95 and 1997-98. And it would appear that the factors of 95/96 for 2004 may not be the result of a three year average. If they were the BPF would have to have been very low indeed. If not, then this makes sense when configuration changes are made to the park as was the case at the K this season.