More on A-Rod’s “Power Surge” in Texas
Yesterday, I was watching ESPN in the wake of Alex Rodriguez’s press conference when some numbers flashed on the screen. It listed at Alex Rodriguez’s isolated power (SLG-AVG) in Texas and New York, showing a much larger number with the former, during the time that he admitted to using steroids. Though it was not explicitly stated, I guess viewers were supposed to infer that this was evidence of A-Rod’s steroid use; or, at least, I can see how someone might interpret these numbers as such.
I previously addressed A-Rod’s power surge in Texas using his home-run rate, and I found the gain was about one home run per season, which is too small to indicate a meaningful change. As I stated in my previous analysis, two problems with using Rodriguez’s raw numbers are that they don’t account for park effects and aging. But, homers are not the only measure of power.
When we go beyond home runs, the analysis changes slightly. The nice thing about aging and home-run rates is that they peak at around age 30, while doubles and triples peak at around age 28. This means that when we compare A-Rod’s extra-base performance in New York to Texas, we are going to expect a decline in doubles and triples from natural aging as well as from moving to a tougher park. In terms of home runs, A-Rod was still on the upswing when he left Texas.
The table below lists A-Rod’s career performance neutralized for park and era effects—these are not his actual numbers, which are polluted by ballpark and era effects—as well as a correction for natural aging. The “Aging (v. Peak)” column reports the percent difference from his projected peak doubles-plus-triples rate (DPT/AB). The aging estimates come from my forthcoming paper on aging in baseball. I base the aging progression towards his peak using the mean of his age 23 and 24 performances to project his peak DPT/AB performance of 5.94% at age 28. This baseline appears to overestimate his future DPT/AB a bit, but all I can do is make an estimate. The DPT/AB projection has the greatest variance fluctuations among the metrics I used to estimate the aging functions of hitters; thus, it’s not surprising to see them fluctuate as they do. However, what the numbers indicate is that his non-homer extra-base hits don’t appear to be vastly different that we would expect given the changes in park and aging, because even if I lowered his expected DPT/AB it would not show a spike during the Texas years.
Year Age Neutral Aging Pred. Neutral Pred. Neutral - DPT/AB (v.Peak)DPT/AB DPT DPT Pred, 1994 18 0.00% -34.15% 3.91% 1995 19 5.10% -27.81% 4.29% 1996 20 8.70% -22.12% 4.63% 1997 21 7.19% -17.08% 4.93% 1998 22 5.83% -12.69% 5.19% 1999 23 4.67% -8.95% 5.41% 2000 24 6.51% -5.86% 5.59% 2001 25 5.41% -3.42% 5.74% 34 36.03 -2.03 2002 26 4.54% -1.63% 5.84% 28 36.05 -8.05 2003 27 5.85% -0.49% 5.91% 35 35.35 -0.35 2004 28 4.32% 0.00% 5.94% Gain 01-03 -10.43 2005 29 5.19% -0.16% 5.93% Gain 01-02 -10.08 2006 30 4.59% -0.97% 5.88% 2007 31 5.45% -2.43% 5.80% 2008 32 6.45% -4.53% 5.67%
One thing to note is that a decrease in doubles and triples could mean an increase in power as a result of those extra-base hits becoming home runs. However, there doesn’t appear to be much of a spike in home runs.
The usual caveats apply to this kind of analysis. What if he’s lying? Well, that would change things, but all I can do is test out his story. What about his admitted use of Ripped Fuel (contained the stimulant ephedra, and was legal) before going to Texas? Again, there is not much I can do here. My aging estimates are based on the past when amphetamine use was widespread, so the aging function may not be steep enough to capture his expected decline, and we can just acknowledge that. What if I used a different time to estimate projected peak age? Yes, that could have an effect, it could go down or up.
The point here is that there is not much to see in these numbers. The so-called “power surge” that we saw in Texas wasn’t all that extraordinary given the park change and aging. And before anyone freaks out, please know that I believe anabolic steroids improve athletic performance, and they ought to help baseball players hit, pitch, run, etc. That there doesn’t appear to be an obvious boost in one player’s numbers doesn’t mean all that much in the grand scheme of things. But, I think it would be a worse sin to look at A-Rod’s numbers and suggest there was a significant power boost from steroids.
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[...] NextRound.net | Level Off From Your Day Job wrote an interesting post today on More on A-Rodâs âPower Surgeâ in TexasHere’s a quick excerptThe aging estimates come from my forthcoming paper on aging in baseball. I base the aging progression towards his peak using the mean of his… [...]