Last night I was at Yankee Stadium to see the home team beat the Giants, 5-1, on a grand slam by Alex Rodriguez in the seventh inning. It was his 24th grand slam, moving him ahead of Lou Gerhig as the all-time career leader in the category.

ARod Hits Record Grand SlamIt’s hard to watch A-Rod at the plate and not think about steroids and PEDs, which got me thinking about how hitting performance in Major League Baseball has trended, particularly in the last few years as the league has taken steps to crack down on cheating.

In 1999, the total MLB batting average (combined for all players in the American & National Leagues), was .271, its highest in 60 years (in 1939 it was .275).

Since 1999, the averages have trended downward, and have declined in particular since 2006, from .269 that year to .255 last year.  That’s a drop of over 5%.

It’s also interesting to note that the American League (which due to its Designated Hitter historically has a higher batting average) has declined even more, at 7.3% over the same period.   A-Rod’s batting average has declined 6.2% since 2006 and 15.3% since his best average as a Yankee in 2005 of .321.

I was surprised to see that the AL batting average is now almost identical to the NL batting average, indicating that the DHs’ decline has contributed significantly since the PED crackdown.