In all of baseball history, there have been 42 player-seasons of 50 or more home runs. That averages out to about one every three seasons.

Of course, they don't all fall in that "average" pattern, and that's kind of the point of this article. Here's the breakdown, and soon you'll see the reason I broke them down this way:

1920-1938: 8
1947-1965: 8
1977-1990: 2
1995-2002: 18
2005-2010: 6

Well. Not only is there one number there that stands out, there are considerable gaps in between the groupings. No one hit 50 home runs or more in a season from 1939-46 (the likely explanation, the departure of much of the talent to World War II) or from 1966-76 (some possible factors: a pitcher's era and labor stoppages). There was a shorter drought from 1991-94, although at least two players (Matt Williams and Ken Griffey Jr.) were on the way to 50+ when the game had its labor stoppage that year. In reality, it's more significant to note that there was just one 50+ homer season (by George Foster) in the 25 years between Willie Mays' 52 in 1965 and Cecil Fielder's 50 in 1990. There were more labor troubles in the game then, and almost no new stadium construction.

I'm sure you have your thoughts about why there were so many 50-homer seasons in just eight years from 1995-2002. I'm not going there in this article. What I do want to know is this: are we again reaching a point where the 50-homer season will become rare, or even have a 25-year period where almost no one hits that many?

In the current period noted above, just one player -- Jose Bautista -- has hit 50 or more (54) since 2007. That's now four seasons completed with only one, and just five other active players have ever hit 50 home runs in a season: Alex Rodriguez (three, and at nearly 37 it doesn't seem likely he'll have another), David Ortiz (ditto on being nearly 37), Jim Thome (not a full-time player any more), Ryan Howard (who will miss much of this season) and Andruw Jones (his 51-homer season in 2005 seems a fluke).

There are a number of potential reasons why this is happening. We appear to be entering a pitchers' era; home runs have declined precipitously in the last 10 years (5458 HR were hit in MLB in 2001, 4552 in 2011, a 17% decline; run scoring in general in 2011 is down 10% from its 2011 level). Several pitcher-friendly stadiums (Petco Park, Comerica Park, Target Field) have opened over the last decade. So is it the pitching? The ballparks? Some other factor, or a combination of many different things? Will anyone hit 50 home runs in 2012?