Was it the PEDs or the park? A look inside A-Rod's Texas numbers
Rodriguez says he used performance-enhancing drugs from 2001 through 2003
Those three years are the best of his career in terms of raw home run production
He also played in 485 of the Rangers' 486 games during those three seasons
While others debate the sincerity and completeness of Alex Rodriguez's confession to Peter Gammons on Monday, let's push past the garment-rending over the impact of his drug use upon the history and integrity of the game, and past the love/hate relationship baseball fans have with Rodriguez, a superstar bizarrely burdened with intense insecurities. Instead, let's take a cold, hard look at the seasons during which Rodriguez admitted he had experimented with banned substances, to see what impact, if any, those substances had on his performance on the field.
If we take Rodriguez at his word, his three years as a Texas Ranger, from 2001 to 2003, were the only seasons during which he used performance-enhancing drugs. In those three seasons he hit 156 home runs. By comparison, in his last three seasons with the Mariners, from 1998 to 2000, he hit 125 and in his first three seasons with the Yankees, from 2004 to 2006, he hit 119. In those six bookend seasons he surpassed 42 homers just once, but in his three seasons in Texas he hit 47 or more every year.
So yes, Rodriguez hit more home runs when he says he was juicing, but was it because he got his power from PEDs, or were there other factors at work? Consider the fact that Rodriguez missed just one game in his three years with Texas, playing in 485 of the Rangers' 486 games over that span. In his first three seasons with the Yankees he played in 14 fewer. In his last three seasons with the Mariners he played in 47 fewer. Rodriguez told Gammons on Monday that a large part of his motivation for experimenting with banned substances was his desire to be able to play every day through the hot Texas summers. In helping him achieve that goal, the drugs clearly worked.
The question then becomes, to what degree did Rodriguez's ill-gotten ability to play every day contribute to the surge in his power numbers. Consider his home-run rates in each of the three-year spans mentioned above (expressed as plate appearances per home run):
SEA '98-00: 15.94 PA/HR
Those figures tell us that not only did Rodriguez take the field more often during his three drug years than in the three-year periods immediately before and after, but he also went deep more often, homering once every 13.92 plate appearances during his time in Texas. Yet, while there's a strong correlation between Rodriguez's drug use and playing time, the source of Rodriguez's power surge lies elsewhere.
Safeco Park, which Rodriguez's Mariners moved into in mid-1999, is a pitcher's park, as was the remodeled Yankee Stadium, the latter of which was particularly hard on right-handed power hitters like Rodriguez. The Ballpark in Arlington (as it was known back then), on the other hand, is a launching pad. Factor in a year-and-a-half of play at the similarly homer-happy Kingdome in 1998 and 1999, and those home-run rates above would seem to correspond to park factors as much or more than to drug use.
To filter out of the effects of his home parks, let's take a second look at Rodriguez's home-run rates using only his performance on the road during each of those three-year spans:
SEA '98-00: 13.61 PA/HR
Here we see that Rodriguez was a better home-run hitter on the road during his last three "clean" seasons with the Mariners than he was during his three years with the Rangers. Those two periods offer a particularly strong comparison because Rodriguez spent all six years in the AL West. Thus, save for moving roughly 12 percent of his road games (10 of 81 annually) from Texas (as a visiting Mariner) to Seattle (as a visiting Ranger), his road games were played in essentially identical environments.
Rodriguez went deep on the road approximately 8 percent less often as a Ranger while playing 12 percent of his road games in a less friendly home-run environment. Given that his Ranger years coincided with his peak-age years (ages 25 to 27), during which an increase in power would have been expected even without the help of illegal substances or a friendlier home park, it's difficult to attribute any of his overall increase in power during those years to the drugs.
In fact, glancing back at those road rates above, there's a superficial appearance of a power decline beginning, not with his first "clean" season in New York in 2004, but with his arrival in Texas in 2001, which is when Rodriguez claimed he started using performance-enhancers. That decline may be superficial in the above numbers, but in reality it ran much deeper, as I first reported in an analysis I did of Rodriguez's career trends for Bronx Banter following the 2004 season. That piece centered on what I referred to as, "a minor, but still unsettling downward trend in Rodriguez's offensive numbers" that "began with Alex's first season in Texas in 2001, but was disguised by his move from the pitcher-friendly Safeco Park ... to the [hitter-friendly] Ballpark in Arlington."