Friday, July 31, 2009

Using BABIP to define The Steroid Era

The idea of The Steroid Era always has kind of been vague. Rumblings of steroid use began back in the 1980s, but sluggers didn't start really launching home runs until the mid-1990s. When did it start? When did it end? What is The Steroid Era?

According to BABIP -- the advanced metric that stands for "batting average on balls in play" -- The Steroid Era lasted from 1993-2001 -- just before the first round of steroid testing began in the major leagues. The era of performance enhancers, though, isn't yet over.

Steroid use isn't just about hitting home runs. Steroid use is about hitting the ball hard. BABIP measures how often a player gets a hit when he puts the ball in play, and the harder the hitter hits the ball, the higher his BABIP is going to be. (Kevin Youkilis leads the Red Sox in BABIP this season because he hits the ball hard so consistently, while Jason Varitek and David Ortiz bring up there rear because they pop the ball up so consistently.)

That particular statistic tells the story of The Steroid Era as well as anything. Check out the progression of the average BABIP across the major leagues over the years. (The list is condensed so your eyes don't glaze over as you read it.)

1986: .286
1988: .285
1990: .287
1992: .285
1994: .299
1996: .304
1998: .301
2000: .302
2002: .292
2004: .298
2006: .303
2008: .300

See the jump? Major-league hitters saw their batting average on balls in play hover around .285 throughout the 1980s only to see it make a huge leap from 1992-94 and spike to an all-time high of .304 in 1996. BABIP numbers didn't drop back below .300 until 2001 (.297) and settled into the low .290s in 2002 and 2003 -- the years in which the first round of steroid testing was negotiated and implemented.

What's disappointing, though, is that BABIP numbers jumped back up over .300 in 2006 and have stayed there for each of the last three seasons. (So far this season, it's at .296, but we haven't investigated whether BABIP numbers rise or fall in the final two months of the season.)

The initial steroid testing appeared to take a huge bite out of the juiced-up line drives that were being knocking all over the ballpark from 1993-2001. But now that those numbers are creeping back up again, it appears that the chemists might once again one step ahead of the enforcement agents.

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