The number of runs scored in Major League games has declined dramatically over the past few years. Runs/Team/Game peaked at 5.14 in the year 2000. In 2013, that number had steadily fallen, all the way to 4.13. That’s a 20% decline in less that 15 seasons.

This changing run environment has led people to say we have entered the Age of the Pitcher. But is that an accurate characterization of what’s going on?

First, let’s look at the decline in runs being scored.

Fewer Long Balls to Dig

Baseball is such a big game it’s easy to lose track of the small things. With thousands of games each year, sometimes we lose track of the big things, too. Take home runs as an example. During the mid-90s to early 2000s, it was commonplace for hitters to launch forty or more home runs out of the ballpark each year. What has happened to the forty home run hitter since 1990?


Year Home Runs HR-2000 Total 40+ HR Hitters
1990 3317 -2375 2
1991 3383 -2309 2
1992 3038 -2654 2
1993 4029 -1663 5
1994 3306 -2386 2
1995 4081 -1611 4
1996 4962 -730 17
1997 4639 -1053 12
1998 5063 -629 13
1999 5528 -164 13
2000 5692 0 16
2001 5458 -234 12
2002 5059 -633 8
2003 5207 -485 9
2004 5451 -241 9
2005 5017 -675 9
2006 5386 -306 11
2007 4957 -735 5
2008 4878 -814 2
2009 5042 -650 5
2010 4613 -1079 2
2011 4552 -1140 2
2012 4934 -758 5
2013 4661 -1031 2

During the height of the home run craze, almost half the teams in baseball had a forty home run hitter. Last year, only two did. There is a line in the film The Usual Suspects where Kevin Spacey describes the disappearance crime lord Keyser Soze by saying, “And like that…he’s gone.” You could almost say the same for the 40 home run hitter.

The middle two columns show the yearly home run total and the difference between each year and the height of the home run era (2000).  Since 2000, the league has witnessed a steady decline — 20% — in the number of home runs.

This decline brings us to the big question: Is baseball witnessing a normal rebalancing to a pre-steroid era or is there a more fundamental shift in the balance between pitching and hitting?

Other Statistics

The changing run environment goes beyond the decline of home runs. Since 1990, the three seasons of 2011-2013 saw the lowest league OBP (.321, .319, .318), the lowest batting average (.255, .255, .253), the highest strikeout percentage (18.6%, 19.8%, 19.9%) and the lowest walk-rate (8.10%, 8.0%, 7.90%).  The last three years have been the worst offensive years since the end of the Cold War.

Given those underlying trends, it’s not surprising that from 2007 to 2013, league FIP fell from 4.47 to 3.87.

From 1993 to 2013, the number of runs scored league-wide fell from 20,862 to 20,255 – and that includes there being two more teams playing in 2013 compared to 1993. The number of runs scored per team has varied from year to year, mostly due to luck-based variation in BABIP. But the general trend is clearly down. I’d like to see a few more years of data to determine if the trends in BA, OBP, BB% and K% continue to put downward pressure on runs/team, or if something else is keeping runs/team relatively constant.

With a stronger steroid testing regime, it was expected there would be fewer runs scored than during the height of the home run craze. But is relative PED-cleanliness the explanation for why batting average and on base percentage are falling? What happened to Moneyball?

Beyond smaller biceps, there are many factors that contribute to this result, including a larger strike zone, smarter defenses, and better bullpen management. But I want to focus on one trend that is not getting much attention: Pitchers are just throwing harder than they used to.

Fastball Velocity

Thanks to the PitchF/x system installed in all MLB stadiums, we are now able to track the speed, rotations, and movement of every pitch in every game. This system started in 2007, so we can’t go back to the early 90s. Yet, here is the average fastball velocity from 2007-2014:

Season FBv
2007 90.3
2008 90.7
2009 91.2
2010 91.2
2011 91.5
2012 91.6
2013 91.7
2014 91.6

That’s a pretty impressive trend. But who, exactly, is throwing harder?

Here are the numbers for starters:

Season FBv K/9
2007 89.8 6.3
2008 90.3 6.45
2009 90.8 6.65
2010 90.7 6.77
2011 91 6.75
2012 91 7.14
2013 91.3 7.19
2014 91.3 7.72

And here are the numbers for relievers:

Year FBv K/9
2007 89.5 6.94
2008 91.7 7.97
2009 91.7 7.3
2010 92.1 7.84
2011 92.8 7.67
2012 93.6 9.9
2013 94 9.36

Starters have picked up a little bit of giddy-up on their fastball, but the big change has come from relievers. In just seven years, relievers have picked up almost five MPH on their fastball and their average K/9 has skyrocketed to 9.36.

For reference, Stephen Strasberg posted a 9.39 K/9 in 2013.

We hear all the time that there are finesse pitchers who can strikeout batters based on their experience and control. That certainly is true, but it doesn’t rule out the argument that fastball velocity plays a very large part in determining a pitchers strikeout rate. Dave Cameron examined the relationship between fastball velocity and strikeouts and found an R^2 of .23. That means that 23% of what you need to know about a pitcher’s strikeout rate is given to you by a radar gun. This is a very large effect, and as Cameron argues at the end of the article, probably the single largest factor that is in control of the pitcher.

[Cameron’s study doesn’t include the possibility that there is a non-linear relationship between K% and vFB. If there is a non-linear relationship, then his findings would understate how important vFB is to strikeouts].

So how important are strikeouts at preventing runs? One article shows that K% was comparable to more complex statistics (FIP, xFIP, SIERA, etc.) at predicting how many runs a pitcher would give up in the future. In other words, strikeout rate appears to be the most important component at explaining how many runs a pitcher will give up in the future.

Take these two together and you start to see a strategy: the single most important statistic to explain how many runs a pitcher will give up is the number of times they record an out without the ball being hit into play. The single biggest factor in determining strikeouts is how hard you throw a baseball.

It looks like MLB front offices have noticed this relationship and are stocking their bullpens with flamethrowers.

So while it is accurate to say that the balance of power has shifted from home plate to the mound, it might be more accurate to say that the real power comes out of the bullpen. And that power is clocked at 94 MPH.