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March 23, 1997
One commonly accept bit of baseball wisdom is that power pitchers -- those
who rely the fastball and strikeouts to
earn their keep, survive longer in the majors than do control pitchers (with
the possible exception of crafty,
one-batter lefties, who apparently can find a job in the majors until they qualify
for Social Security). The repeated
chances given to young fireballers who impress scouts with their velocity is
a testament to the love affair with power
pitchers that has persisted for years.
But is there any basis for this belief? Do pitchers with high strikeout rates
have any better chances for success
than do comparably performing same-age pitchers with low strikeout rates? I
decided to answer the question by
researching the fortunes of such pitchers in the study presented below.
The study compares groups of pitchers with similar ERA's at age 25 who differed
by strikeout rate, and seeing how
they did 5 years later. The goal was to determine whether high-strikeout rates
pitchers aged better as a group, as is
commonly believed.
In this study, I took pitchers who pitched 150 or more innings at age 25 for
a single team (pitchers who split
time with 2 or more clubs at age 25 were excluded for computational simplicity).
I compared each pitcher's
strikeout rate to the league's average in that year. Pitchers at or above the
league average fell into one
group, those below league average fell into another.
I broke each group into ERA+ cohorts -- that is, all pitchers with similar
park and league adjusted ERA's were
grouped together. ERA+ is defined in Total Baseball, and the chart below shows
the ranges I used to divide
the groups (assuming a league average ERA of 4.50):
ERA+ Range ERA Range ------- ----------- 60- 79 5.70 - 7.50 80- 99 4.50 - 5.70 100-119 3.80 - 4.50 120-139 3.20 - 3.80 140-159 2.80 - 3.20I totalled the performance for each strikeout group's ERA+ cohort at age 25, and looked at how many of them were still pitching at age 30. I also looked at their age 30 performance -- averaged innings pitched, ERA, and ERA+.
Range : ERA+ Cohort range (the upper and lower bounds on
ERA+ for that group)
K : Strikeout rate group
G -> Greater than or equal to league average
L -> Less than league average
#Pit : The number of pitchers is this group
IP : Averaged number of innings pitched
ERA : Collective Earned Run Average (unadjusted) for the group
ERA+ : Park and league normalized collective ERA
% Active : Percentage of pitchers from this group who
appeared in the majors at age 30
Data is through 1993, and excludes then-active pitchers who hadn't reached age
30 as of 1993. Minimum 10 pitchers per strikeout rate/ERA+ group.
Age 25 Age 30 Range K #Pit IP ERA ERA+ %Active IP ERA ERA+ ----------------------------- ---------------------- 60-79 G 16 189 4.50 74 38% 210 3.22 116 60-79 L 19 186 5.05 74 37% 131 3.29 116
80-99 G 89 215 3.95 92 62% 159 3.58 111 80-99 L 130 213 4.02 90 52% 129 3.91 100
100-119 G 121 243 3.34 109 61% 168 3.63 105 100-119 L 143 229 3.40 110 55% 167 3.78 105
120-139 G 84 254 2.85 128 75% 177 3.20 117 120-139 L 45 244 2.91 126 69% 167 3.53 108
140-159 G 37 261 2.53 147 76% 195 3.19 121 140-159 L 10 252 2.33 148 70% 180 3.69 102
The comparison between the G/L groups for each ERA+ cohorts are striking in their similarity -- in almost all cases, their ERA's and innings pitched are close enough to be all but equal. High strikeout pitchers tend to pitch a few more innings (the most significant gap being the 14 IP gap among the 100-119 cohort), but otherwise it's hard to distinguish the two groups at age 25 in any way other than strikeout rate.
The look at age 30 shows how the groups have diverged. The percentage of pitchers still active is higher in every cohort, ranging from the negligible difference in the 60-79 cohort to 10 percentage points in the 80-99 cohort, averaging out a consistent gap of 5-7% in favor of the high strikeout pitchers.
What's even more striking is the differences in performance at age 30 among
those still active. In every case, the
high strikeout pitchers are throwing more innings -- and the gaps are significant
with the exception of the 100-119 cohort. High strikeout pitchers are throwing
20 or so innings more per year than their low-strikeout counterparts. The results
are more impressive too. In three of the groups, the high strikeout pitchers
are posting adjusted ERA's 10-15% higher than low-strikeout pitchers were. And
in the other two cases (60-79 and 100-119) the rates of run prevention were
identical.
There is *no* case in any cohort where the high strikeout pitchers were throwing fewer innings, or at a worse rate of performance than low strikeout pitchers were at age 30. And in several instances, there was a distinct trend towards such pitchers being more likely to have a job, to throw more innings, and to post better ERA's.
The combined impact of each of these findings makes it clear that, while not a foolproof indicator by any means, we can make better predictions about how pitchers will age by looking at their strikeout rates when they are young.[ Home ] [ Library ] [ Bookstore ] [ Contact ] [ Search ]
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Copyright 1997-2001 by Keith Woolner. All included authors retain the copyrights to their original works.