Proof That the Steroid-Era Power Surge in Major League Baseball Has Been Stopped

Zachary D. Rymer@zachrymerMLB Lead WriterMay 22, 2013

The Steroid Era isn't that far in the rear-view mirror. Major League Baseball hasn't even been testing for PEDs for a decade yet, and it was only a dozen years ago that Barry Bonds broke the single-season home run record.

However, the point stands that the Steroid Era is in the rear-view mirror. You can tell just by looking around, as you just don't see that many Incredible Hulk lookalikes wearing baseball uniforms anymore.

That, and you can also tell by looking at the numbers.

I did so back in January, but only in a scratch-the-surface sort of fashion. I took a deeper dive into the numbers this week and found a heck of a lot more worth talking about. There are plenty of numbers that can highlight just how obvious it is that there was some unnatural power in the game, and how obvious it is now that it's gone away.

When did the Steroid Era officially begin? That there is a question without a definitive answer, but ESPN probably has the right idea in saying that it likely started in the late 1980s, with power numbers taking a noticeable hike in the '90s.

Isolated Power (ISO) is a stat that can help us out here. Found on FanGraphs and various other websites, it's a stat that measures how good players are hitting for extra bases. My usual line is to think of it as a slugging percentage that ignores singles.

Per league data from FanGraphs, here's a look at the league's ISO from 1988 to 2012 as produced by all non-pitchers:

Power skyrocketed in the early '90s to a peak in '94, and it didn't progress below that peak until recently. And while there hasn't been a straight downhill decline since MLB put its testing and penalties system in place in 2005, there hasn't been as much power these last few years. The trend is a little more clear if we break it down into averages for different time periods:

  • 1988-1993: .130
  • 1994-1999: .159
  • 2000-2004: .165
  • 2005-2012: .156

There's still more power in the game today than there was in the late '80s and early '90s, but not as much as there was between 1994 and 2004, the last year before testing. Power has declined even more in the years since the Mitchell Report was released late in 2007, as the average ISO between 2008 to 2012 measures out to .153.

The general deflation of power also shows up in the average number of home runs per game hit in these same eras. With numbers courtesy of Baseball-Reference.com:

  • 1988-1993: 0.88
  • 1994-1999: 1.06
  • 2000-2004: 1.10
  • 2005-2012: 1.01
  • (2008-2012: 0.99)

Once again, still more power now than there was in the late '80s and early '90s, but not as much as there was in the Steroid Era.

The home run decline can also be seen in the leaderboards. The Steroid Era saw an explosion of 40-homer seasons, which have since gone back to being special occasions. Once again with a nod to Baseball-Reference.com:

Year 40-Homer Players High
 1988 42 
 1989 47 
 1990 51 
 1991 44
 1992 43
 1993 46
 1994* 43
 1995 50
 1996 17  52
 1997 12  58
 1998 13  70
 1999 13  65
 2000 16  50
 2001 12 73
 2002 57
 2003 10  47
 2004 48
 2005 51
 2006 11  58
 2007 54
 2008 48
 2009 47
 2010 54
 2011 2 43
 2012 44

*At the time the strike cut the 1994 season short in mid-August, there were four players in the 36-39 range. They likely would have topped 40 homers had the season continued.

Just look at all those 40-homer seasons between 1996 and 2001. There were 83 40-homer seasons in that span, and that's out of 310 40-homer seasons in MLB history.

That means 27 percent of all 40-homer seasons happened in that six-year window between 1996 and 2001. Stretch it out a bit further to 2006, and 42 percent of MLB's 40-homer seasons happened in an 11-year span.

We saw an uptick in 40-homer seasons last year, but not an alarming one. Nobody touched 45 homers, and the only player to top 40 who didn't come into the year as a known slugger was Toronto Blue Jays first baseman/DH Edwin Encarnacion, and he's doing it again this season.

Encarnacion's success isn't entirely mysterious, either, as Jack Moore of Sports On Earth pointed out that Encarnacion started blasting homers after making "significant" changes to his swing and approach at the plate. Natural stuff, that.

Another reason not to be suspicious of Encarnacion is the fact that he's still in his prime years. The same cannot be said of many of the guys who were blasting homers out of the yard during the juicing era.

Babe Ruth achieved baseball's first 40-homer season in 1920 when he blasted 54 out of the yard at the age of 25. From then right up until 1995, the average age for a 40-homer hitter was 28.2 years old. That's right in prime territory.

From 1996 to 2001, the average was a bit older: 29.5 years old. Stretch things out from 1996 to 2006, and the average age barely budges up to 29.6.

From 2007 to 2012, the average age for a 40-homer hitter went down again to 28.5, roughly where it was for so many years before the Steroid Era.

This speaks to one of the things we know PEDs can do for ballplayers. They essentially make them superhuman, and that's a life that comes with both increased strength and increased longevity. Old guys were doing things in the juiced-up era that old guys generally have no business doing.

Case in point, there have been 24 cases in MLB history of a player 35 years old or older hitting at least 40 HRs. Of those, 13 occurred between 1996 and 2006.

That was mostly Barry Bonds' doing, granted, but he wasn't the only old-timer hitting for an unusual amount of power in the Steroid Era. Take a look at the ISO splits between non-pitchers 34 years old or younger and non-pitchers 35 years old or older between 1988 and 2012:

The older guys were actually showing younger guys up in the power department for a while there, but the pendulum has swung back toward the non-ancient. Things have gone back to normal.

There's still power to be found in baseball. For that matter, there's no point ignoring the uptick in power that occurred last year after two very rough years for power hitters in 2010 and 2011. Things are staying steady so far in 2013, as the league's non-pitcher ISO is exactly where it was last year, and there are 1.02 home runs being hit per game. That, also, is the same as last year.

But these numbers aren't worth freaking out over. If anything, they indicate that hitters have figured out how to have a fighting chance against the league's pitchers, not that juice is finding its way back into the game.

Indeed, we know from what happened in the early '90s and what came after what it looks like when juice spreads. Power numbers inflated to an absurd degree, and it wasn't until law came to the land that the numbers began to deflate toward the norm.

It pretty much goes without saying that there are still juicers in the game today. Just not enough of them to pump the power numbers back up to where they were when the land was lawless and the juicers were allowed to roam free in great numbers.

It was good fun while we were all ignorant. Now that we're not, we should all be able to agree with the following sentiment: Let's not go through all that again. 

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