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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