OT – What caused MLB to set a record for Home Runs in a Month?

Roids suck.

because it has never, ever been true.  Baseball's hagiographical marketing has pushed that view in order to broaden the appeal of their game, but any look at the numbers will reveal that for the falsehood that it is.

Before I begin, I too admire Aaron for what he had to overcome, in chasing a revered record set by a white man playing for the most storied franchise in baseball (in fact, perhaps in any team sport; I'm not familiar enough with soccer history to pursue that claim), while playing in the Deep South, while the tumult of the Civil Rights Era exacerbated racial tensions.  (Did you know that Aaron was the last full-time MLB player to play in the Negro Leagues first?)  He was an amazing player and far more gracious a man than I think I would be in his place. The first game I went to was his last year in the league, so I got to see him (as a shell of himself, alas) against the Pirates as a kid.

"[...] baseball has the unique privilege to be a "timeless" sport that despite changes in athleticism and equipment can compare players directly from 50 years apart."

Um, no.  There is no comparison between players from different eras in baseball; the conditions of competition are simply too different.

To list but a few issues, Ruth played 154 game seasons against 2/3rds the players, with no African-American or foreign-born players to speak of.  Bob Gibson was the fastest pitcher in baseball during his era; today every team has someone who can pitch faster than his best.  MLB wasn't a truly international sport until sometime in the late 80's, when foreign players started coming over in clumps.  When Ruth played, it was stasticially likely that someone elsewhere in the world was a better baseball player than he was(!), but these days the very best players in the world gravitate to the US.

That's before we discuss changes to the gloves (have you seen one of the gloves that Ruth used?), ball (the making of baseballs is oddly fascinating for something that in theory hasn't changed that much), bats (ash vs. maple bats alone make a measurable difference), or fielding (not only have fielders been getting steadly better, but the practice of shifting has made a large difference in the efficiency of fielders), and stadium layouts.

That's the conditions of competition.  The competitors themselves?  They have benefitted from the vastly increased knowledge about human bodies and athletic biology (of which, yes, steroids plays a part), nutrition, weight training, and how to remain both flexible and strong.  This knowledge was always out there, but today's athlete gets it from day one, and has it reinforced by every coach/trainer he meets, as opposed to having to do it for himself.  When Kareem Abdul-Jabbar took up yoga, he was seen as a freak who was frittering away precious practice time he could be using for weights or running.  Yet that helped him to play for much much longer than any seven-footer ever had before.  Nowadays every team incorporates that kind of training, indeed even tailoring it to the individual.  And if they get hurt, like Dizzy Dean breaking a toe, or Smoky Joe Wood hurting his leg?  They get medical care and aren't allowed to compound the injury, as both of them did, resulting in shoulder tears which forced them from the game.  And if they did tear up their shoulder?  Today surgery can fix that, if not at 100%, at a rate much better than zero.

Now, this doesn't make as much difference at the top - the top 0.01% are still approaching the physical limits of the human body.  The big difference?  If Bob Gibson was transplanted from his peak into today's game, he'd be a lot more humdrum than we liked to think, simply because instead of being Wally Pipp, the average player he'd face is a lot more like Gehrig.

TL,DR:  Baseball comparisons between eras are an illusion deliberately fostered by MLB to market the game.

In Part II, I'll talk about steroids and why baseball is portraying them as evil.

The answer lies in the same place it usually does: money.

Going back to 1997, the owners had recently been spanked in court for colluding to hold down the price of free agents.  Baseball had hit its first ever work stoppage, which had made a big dent in baseball fandom and was widely seen as the fault of ownership (coming on the heels of the blatant collusion issues).  Free agency was growing salaries extremely rapidly, to the point that owners who didn't want to pay market rates were pushing the comissioner to Do Something to hold those uppity players back from making so much money.

And a reporter asks Mark McGuire about the andro in his locker.

At the time, andro was available over the counter.  It wasn't illegal or controlled in the US, and was certainly not on baseball's list of prohibited substances.  But it was a steroid precurser.

As McGuire chased down Ruth and Maris, and was chased by Sosa in turn, crowds flocked to the park.  Baseball regained the attendance it had lost with labor disputes and then some.  Ownership got behind and pushed, knowing a good thing when they saw one.  And while today "[Parents] don't tell their children about the McGwire-Sosa chase because they were both juiced out of their minds and everybody knows it.", that wasn't true then - baseball seemingly got a whole new generation of fans thanks to the Long Ball.

Now cast your eyes to the negotiating table.  The feds have just raided a drug lab in California, and it seems likely that some of baseball's biggest stars are connected to it.  Ownership knows baseball has a PED issue - they've known for a while now, and the "anonymous" survey testing they conducted confirmed it.  Armed with this information, pressured by ownership to hold costs down, and with a need for leverage over the player's union, what does ownership do?  They leak the survey test results (all but confirmed in the final legal proceedings against Bonds and Clemens), and begin a campaign to paint steroids as a uniquely damaging substance that's entirely the player's fault, deliberately ignoring (and in Selig's case, actively denying) the role ownership may have played.

This was, as best science can tell, a lie.  While steroids are more effective muscle builders than other PEDs, they are not more effective for hitters than pitchers (Carroll and others), they are not more effective for stars than scrubs (quite the opposite), and their effect for most MLB players is of the same magnitude as other legal advantages (e.g. harder bats, contacts to turn 20/25 into 20/15, adjustments to weight and flexibility training, biomechanical analysis of your pitching motiion, etc.).  In short, while steroids likely do provide an advantage, it is not unique, can be duplicated, and doesn't create a qualitative difference the game.  It simply isn't "a wholesale corruption of the dynamics of the sport in that era." no matter what the league's marketing tells you.

For comparison, look at Bob Beamon's long jump.  He increased the old record by 20%(!) based largely on two factors (perfect timing on his takeoff and the first ever Olympics at 7000 feet).  That's a wholesale change in the dynamics of a sport.  It took 30 years before anyone could match that.  By comparion, McGuire and Sosa pushed the boundaries by ~10% - in 5% more games.

TL,DR:  The perception of modern PEDs as a uniquely corrupting influence on baseball is based largely on ownership's wildly successful pushing of that position to help break the player's union.  It is not in any way based on science or historical analysis, only on perception.