Quirky Anaheim outfielder Torii Hunter, when asked about the sudden and significant drop in home runs over the last five years, had this to say:

“I think the steroid testing has something to do with it,” he said. “If there were any guys who were taking it, they’re not taking it anymore. I’d say it’s a small percentage, but of course it’s going to have an impact.”

Decided to look up the last 10 years, since the Summer of 1998 was the memorable one when heads were buried in the sand, and McGwire and Sosa cheated their way to 70 and 66, respectively.

2008 4876 home runs
2007 4957 home runs
2006 5386 home runs
2005 5017 home runs
2004 5451 home runs
2003 5207 home runs
2002 5059 home runs
2001 5458 home runs
2000 5693 home runs
1999 5528 home runs
1998 5064 home runs

So Sosa and McGwire explode, and then home run totals surge for the next two years. But Tony LaRussa, who still doesn’t think Big Red juiced, might point out how in 2002 and 2005, home run totals dipped. He might even argue that 2006 was just a random year.

Baseball Reference