Foul Area Vs. Strikeouts: 1969-2000

An inverse relationship between foul territory area (AF) and strikeouts (S0) in the AL from 1954-1968, and in the NL from 1964-68, has been established.  Did the relationship persist in subsequent years?   Previously reported methods  were used to analyze AL stadiums in use 2 or more years from 1969-2000 . 

Nineteen teams/stadiums and 320,343 SO were analyzed (Table 1).  The individual teams/parks ranged from 5 to 31 years of use, and from 27,507 (Oakland) to 5,016 (Jacobs Field) in total SO. 

Table 1.  19 AL Stadiums in use from 1969-2000, with average yearly and total SO.

The same previously-reported method of measuring and graphing  average team/park  SO versus AF rank during the entire period was applied in Fig.  1.

Fig. 1. Average yearly SO for 19 teams/ballparks used 2 or more years 1969-2000.  Although an upward trendline is evident in qualitative rank order analysis, 9 ballparks with smallest AF (right) actually had significantly fewer SO on cumulative ( 165,322 vs 138,978 ) and individual yearly average (879 to 852) SO in quantitative comparison to the largest 9 (left).

However, despite an anticipated qualitative trendline of increasing SO with decrease in AF for individual stadiums for the entire cohort, closer quantitative analysis of the 9 teams/stadiums with the greatest AF showed they  actually averaged more SO than the 9 with lowest A (879 vs. 842).  Furthermore, a highly significant difference in average yearly SO was identified for the 340 SO-years analyzed (p=0.004), including 188 SO-yrs. for the largest 9 AF vs. 152 SO-yrs. for the smallest 9.  When study was adjusted to equalize total numbers of seasons in each group (n=183), significant differences were still identified (p=0.05).  The apparent qualitative trendline of rank order analysis derives, at least in part, from Texas’ and Cleveland’s position at the far right of the graph, both with high SO numbers, but few seasons of play and fewer total SO.  When the 31-year period was divided into 4 to 6--season segments with strike years ’81, ’94, ’95, excluded, each period exhibited a downward trend of SO with decreased AF.

Fig. 2: Six periods from 1969 to 2000 (1981, 1994-5 strike years not included). The most recent 1996-2000 period (lower Rt) exhibits the most dramatic reversal of anticipated inverse correlation between AF and SO, reflecting a statistically significant direct relationship of SO and AF (p=0.004).

Therefore, the previous inverse quantitative relationship identified in analysis of 226,761 SO from 1954-68 seems to be replaced by a direct quantitative correlation between AF and SO during the 1969-2000 period: the larger the stadium AF, the greater the SO.  A number of factors may contribute to the reversal:

1)      Analysis including multiple eras with changes in approach to hitting and to pitching and SO over multiple eras, including the end of the 64-72 dead ball era, the ground-ball Astroturf era, the DH era, the steroid era.

2)      An increase in teams/parks brought about by expansion, with varying contributions in terms of numbers of years to the analysis, may have contributed to qualitative and quantitative inability  to demonstrate anticipated relationships. 

3)      A decrease in total foul balls due to a lower upper edge of the strike zone, and a lowering of mound height of 1969.  Where no tabulation of foul balls dating to 1954 is available, it currently remains beyond the scope of this research to analyze that contribution more closely.  Did fewer foul balls, make it additionally more difficult to get a SO than in the ’54-68 era?

Certainly, analysis of hitters' SO in each ballpark, as opposed to both home and way, is now indicated.

If the relationship of AF and SO was reversed from ’69-00, with greatest disparities in the most relevant, most recent, period of analysis (96-’00), what happened from ’00- 04 at the end of the steroid era, or from ’05-10?