League Factors

Using Park Factors

© Tangotiger

Bill Felber, in an excellent interview conducted by Steve Lombardi at NetShrine.com, remarked that Sportsman's Park was home for two teams for a period of years. Another reader at BaseballThinkFactory.org also noted that Shibe Park had a similar situation. However, as Bill noted, the park factors for the two St Louis teams were not the same. Since a park factor compares how a team and its opponent perform at home and on the road, we have a unique situation here. The opponent parks for the Cardinals and the Browns are not the same. The park factors are factors relative to other parks in the same league. Bill's discovery is important, as we can compare parks of different leagues, using the one common park (Sportsman's Park) as the baseline. And to add more power to this, Shibe Park was also in the same situation. Here's the relevant data, for 1938-1953 (source of data is from Yahoo eGroup: kjokbaseball)

ParkID	TeamID	LgID	 RS_H 	 RA_H 	 RS_A 	 RA_A 	RS_x	RA_x	R_x
PHI11	PHA	AL	 4.25 	 5.08 	 4.04 	 4.98 	 1.051 	 1.020 	 1.034
PHI11	PHI	NL	 3.71 	 4.44 	 3.80 	 4.75 	 0.977 	 0.933 	 0.952
STL07	SLA	AL	 4.59 	 5.28 	 3.98 	 4.91 	 1.155 	 1.077 	 1.112
STL07	SLN	NL	 4.95 	 3.94 	 4.50 	 3.93 	 1.101 	 1.003 	 1.056

Here's how to read that first line: the AL Philadelphia team (the A's) scored 4.25 runs at Shibe Park, and allowed 5.08 runs. When playing at one of the other AL parks, they scored 4.04 runs and allowed 4.98 runs. They scored 5% and allowed 2% more runs at home than on the road. The overall average is +3%.

Simple enough?

Now, look what happens with the Phillies, who are in the NL. They scored and allowed more runs on the road! That's right, 5% more runs were scored on the road than at Shibe Park. What does this mean? It means that there were more hitter's parks in the NL than in the AL. And, by a whopping 8.6% factor.

To add support to the argument, the Browns in the AL and the Cardinals in the NL also played in the same park at the exact same time that the two Philly teams played at Shibe. And what were the results? The Browns scored and allowed 11% more runs at Sportsman's than in other AL parks. The Cardinals only scored and allowed 6% more runs at Sportsman's than in other NL parks. The reason is clear: the other NL parks were easier in which to score runs. The factor based on the St Louis teams is 5.3%.

Why is it also not 8 or 9%? Because all parks affect all hitters and pitchers in different ways. The players on these teams are not necessarily representative of the whole population. I made additional comments on park factors in an article a few years ago.

Are there other teams that shared parks? You betcha. Here's the full chart. Rather clear that we find more hitter's parks in the NL than the AL. Thanks Bill, that was fun.

 

First Year Last Year Num Of Years Park LgID Team GP_H RS_H RA_H GP_A RS_A RA_A RS_x RA_x R_x Hitter's Parks in…
1903 1903 1 Columbia Park AL Athletics 67 4.82 3.55 70 3.91 4.01 1.23 0.88 1.06 NL
1903 1903 1 Columbia Park NL Phillies 16 3.81 3.75 78 4.71 5.64 0.81 0.66 0.73
 
1911 1911 1 Hilltop Park AL Yankees 77 4.74 5.48 76 4.2 3.96 1.13 1.38 1.25 NL
1911 1911 1 Hilltop Park NL Giants 28 5.07 3.46 79 5.05 3.48 1 1 1
 
1912 1922 11 Polo Grounds AL Yankees 762 4.35 3.84 819 4.07 4.11 1.07 0.93 1 NL
1912 1922 11 Polo Grounds NL Giants 834 4.36 3.46 828 4.61 3.73 0.94 0.93 0.94
 
1914 1915 2 Fenway Park AL Red Sox 155 3.84 3.01 159 4.17 3.41 0.92 0.88 0.9 AL
1914 1915 2 Fenway Park NL Braves 80 4.08 3.41 158 3.92 3.49 1.04 0.98 1.01
 
1920 1953 34 Sportsman's AL Browns 2622 4.99 5.49 2628 4.21 5.1 1.18 1.08 1.12 NL
1920 1953 34 Sportsman's NL Cardinals 2619 5.12 4.25 2621 4.77 4.3 1.07 0.99 1.03
 
1927 1954 18 Shibe Park AL Athletics 1384 4.26 5.09 1398 4.1 5 1.04 1.02 1.03 NL
1927 1954 18 Shibe Park NL Phillies 1291 3.74 4.41 1391 3.85 4.79 0.97 0.92 0.94
 
1929 1932 4 Braves Field AL Red Sox 50 3.8 5 305 3.82 5.83 0.99 0.86 0.91 NL
1929 1932 4 Braves Field NL Braves 309 3.96 4.55 310 4.22 5.29 0.94 0.86 0.9
 
1962 1965 4 Dodger Stadium AL Angels 323 3.46 3.57 324 3.92 4.11 0.88 0.87 0.88 NL
1962 1965 4 Dodger Stadium NL Dodgers 326 3.78 3.11 328 4.49 4.04 0.84 0.77 0.81
 
1974 1975 2 Shea Stadium AL Yankees 159 4.06 3.64 163 4.33 3.88 0.94 0.94 0.94 NL
1974 1975 2 Shea Stadium NL Mets 162 3.54 3.86 162 3.98 3.98 0.89 0.97 0.93