One day in college, when my schedule had no pressing matters outside of what brand of cheap beer to buy later in the evening, a friend and I talked about global warming. We had opposing viewpoints though neither of us had any expertise or really anything more than anecdotal evidence, but it was a civil conversation with a respectful and earnest back-and-forth taking place. To simplify the already simple perspectives of two 20 year-olds smoking cigarettes on a balcony on a Tuesday afternoon, he pointed to a lack of statistical data from which to draw any conclusions on how human activity impacted the fluctuation of greenhouse gasses and climate change and I maintained that it seemed willfully ignorant to think that the amount of chemicals we as a species pumped into the air on a daily or hourly basis couldn’t have a detrimental effect on our planet and its ecology.

I mention this because I’ve found I make the same argument when talking about the impact of widespread steroid use in baseball, specifically the offensive numbers put up during that time. The numbers show a significant spike in run production, particularly by way of extra-base hits and homers, from 1993-2009. During those 17 seasons, the runs scored per game league-wide stayed north of 4.6 and slugging percentage was over .400 (three of the most pronounced seasons of offensive uptick were 1996, 1999, and 2000, which had 5.04, 5.08, and 5.14 R/G respectively). Home runs per game stayed above 1.0 from 1994-2009, with the apex coming from 1999-2001 (the average over those three years being 1.14 HR/G).

Now, there has been offensive fluctuation throughout baseball history, but the last time baseball averaged five runs per game in a season before 1996 was 1936. In addition, 1987 was the first year in baseball’s history that a season featured over one home run per game. In fact, 1987 is a pretty significant year in all this; it will likely be seen as the first official year of baseball’s “Steroid Era” as it featured young players Mark McGwire and Jose Canseco belting 49 and 31 homers, respectively (though a 32 year-old Andre Dawson also hit 49 that year), and the emergence of extreme strength and conditioning programs in major league clubhouses.

For a moment, 1987 looked like an anomaly as season-long offensive totals and averages drifted back down to expected totals. In fact, 1988, 1989, and 1992 featured the lowest runs per game, homers per game, and league-wide SLG since 1981. Steroids were likely a young man’s game in the sport and those years also served to expand the customer base for PEDs while veterans who may have been more partial to amphetamines than Human Growth Hormone made their way closer to retirement. Then, of course, 1993 kicked off a run of sustained offensive dominance.

During that stretch there are some examples people remember more than others. Outside of Bonds, Palmeiro, Sosa and the like, there was Brady Anderson’s famous 50 home run explosion in 1996 and the infamously muscular Bret Boone of 2001-2004 who averaged 30 homers a season. But perhaps most striking is looking at the highest individual seasons of isolated slugging in history. From 1970 to present, 82% of players who had the top 100 seasons in terms of ISO were from seasons between 1994 and now. Going back to 1900, 50% were from that same timeframe. Some notable seasons from that period include Tony Clark in 2005 (.332 ISO, #83 all-time), Anderson’s 1996 (.340, #70), Carlos Pena in 2007 (.345, #55), and Javy Lopez in 2003 (.359, good for the 31st highest ISO in a season ever).

Major League Baseball wasn’t ignorant about steroid usage. The 1980s had ended with one of the most notable punishments for steroid use to that point when Ben Johnson was stripped of his gold medal for testing positive for an anabolic steroid, leading to President Reagan signing a bill to outlaw the sale of non-prescription steroids a month and a half later. In July of 1991, MLB Commissioner Fay Vincent “banned” the use of steroids by sending out a memo full of vague guidelines for testing and punishment and only one specific mention of steroids (brought up in a paragraph regarding prescription drugs). In reality, Vincent’s memo focused more on substance abuse than performance enhancing drugs—cocaine and amphetamines were a more public and widespread problem through most of the ‘80s and most of Vincent’s memo focuses on “illegal drugs” and how they “can cause […] diminished job performance”.

Perhaps the moment when baseball most displayed its ambivalence (at the time) toward preventing rampant steroid usage was in 1997, when Bud Selig essentially reissued the same memo with only one notable change—adding some clarification to the “Discipline” portion of the memo. Whereas Vincent’s memo had only mentioned the offer of a rehabilitation program for players testing positive for the first time, Selig added that those players would also be required to participate in the testing program. Both memos explicitly mention that major leaguers with no prior positive tests were not subject to random testing, would not be tested more than four times a year (though it’s likely some or many were never tested at all), and all consequences for failed tests were only described as “immediate discipline” of a non-specific nature.

2005 was one of the first blips on the radar in terms of the offensive trend reversing. It started off slow, with an April that featured the lowest league-wide rate of homers per plate appearance for that month since 1997. This became one of the first periods in which baseball writers began to collectively wonder if steroid testing was going to have a chilling effect on offense from here forward. It wasn’t coincidental, the congressional hearings which resulted in an improved and potent Joint Drug Prevention and Treatment Program had taken place the offseason before and the new policies had been implemented for the 2005 season. Most of this had come following 1998 and McGwire and Sosa’s chase to break Roger Maris’ single-season home run record. Reporter Steve Wilstein noticed a bottle of andro in Mark McGwire’s locker during an interview during that season and four years later baseball had its first agreement on serious drug testing. In 2004, random testing and substantial penalties for positive tests were implemented, which was improved over the next two years to result in a policy close to what we have today.

In hindsight, 2005 turned out to be an aberration as run production per game, slugging percentage, and homers per game returned to earlier rates until 2010. From 2010 to now, runs per game has been below 4.4 in each season, league-wide SLG has not broken .405 and homers per game has only broken 1.0 once (in 2012, when it was 1.02). Since then, the idea that steroid testing with meaningful consequences caused a league-wide dip in offensive prowess has been debated and mulled over by many baseball writers.

Nate Silver has probably written one of the best analyses of this debate so far. His words are much more intelligent than mine on the matter, I suggest you read it. To wit, Silver’s piece demonstrates that there isn’t much evidence to suggest a minority of major leaguers getting a disproportionate boost from PED usage. It’s not, though, that it disproves an advantage hitters achieved by using PEDs, but rather that PED use was likely spread out amongst star players and underachieving players looking for a boost. In fact, Will Carroll’s book The Juice offers an in-depth look into the murky ethics and legality of controlled substances, supplements, and steroids as well as the usage by replacement-level players looking to snag a more prominent role than established stars (as these players are much more likely to benefit from the usage than pre-existing star players).

Murky also describes trying to untangle how PEDs and the subsequent testing that was put into place effect the game played in front of us now. Offense has stayed half a run or more below the seasons of the Steroid Era since 2010 and league-wide slugging percentage has dropped every season since 2006 excepting one spike in 2012. There is enough there to suggest a trend becoming the new norm, namely that the game objectively features less offense in the last four seasons than it’s seen since before 1993. This could be because PED testing, enforcement, and the players’ adherence to these new rules have become more widely understood and accepted. It could also just be a perfect storm of better pitching and fewer young power hitters coming up to replace the waves of retiring sluggers, ‘roided up or not.

Cork Gaines pointed out in April 2014 that the league-wide rate for homers hit per fly ball hasn’t fallen correspondingly with that of homers per game, which could be more due to pitchers being instructed to pitch lower in the zone than a dearth of PED usage in the game. On top of that, defensive shifts are being employed more often by more teams and defensive metrics have made some teams construct their rosters with run prevention in mind more than assembling a formidable lineup. Some think the banning of amphetamines has done more than banning steroids. There are a lot of additional factors that, combined, have helped create the pitching-dominated game we’re seeing now.

Baseball is a complex, intricate, and ever-changing game and one that has too many variables for a single one to tip the balance too far in either direction. Performance enhancers did a lot to bloat offensive numbers in ‘90s and ‘00s; the measures Major League Baseball took to remove them from the sport may not be the sole explanation for reduced offense in the first half of the ‘10s, but—as I felt concerning climate change in college—one can’t deny it’s had a significant effect.