Sunday, March 31, 2013

The Relationship Between Batting Average and OBP

This is one of the strangest charts I’ve seen in some time:

This isn’t something you see every day. What I did was chart the year-on-year changes in batting average and OBP, assuming there had to be a correlation (and of course there is—batting average is a function of OBP). When I generated this chart, I had no idea to expect that OBP would march in such lockstep with batting average.

But I should have. I used a version of this chart in a recent post:

While OBP has fluctuated over this 60-year period, the gap between batting average and OBP has remained a fairly steady 60 points. This is because the walks per game has remained relatively stable in that time frame (you can see that chart in the post titled “Strikeouts in Baseball”). There are a handful of players who have OBPs 100 or more points greater than their batting averages, but fewer than you think—from 2009-12, there were only 32 seasons (out of approximately 4,000 season-years of hitting) where a batter hit at least .250 and had an OBP of at least .350—lower that gap closer to 60 points, and a player is well-advised to be hitting at least .270 or so, and this in an era where the major league batting average last year was .255. ONE person walked over 100 times last year (Adam Dunn, and with a .204 batting average, he better have). People can talk all they want about “He makes up for it by walking,” but very few do. In an era of reduced offense, it would behoove hitters to become more selective at the plate.

Strikeouts in Baseball

There was a really good article in the Wall Street Journal on March 29th titled “Baseball 2013: Here Come the Flamethrowers (chances are the link will work only for WSJ subscribers, however, if you copy and paste the title, you just might be able to read it. Be sure to NOT mention my name). One of the main points was the increase in strikeouts (the article stated an 18.3% increase since 2003). I’ll expand on some of that discussion with some historical charts. Unless otherwise stated, all information is generated from This first chart shows the incidence of strikeouts and walks from 1901-2012:

It’s pretty interesting how in lockstep walks and strikeouts were until 1950, at which time a very distinct divergence began that hasn’t stopped since. Up until 1950, both walks AND strikeouts were increasing, but walks began to decrease and strikeouts, after ebbing and flowing, have begun a steady upward trend since around 1980. Smarter people than me can probably explain why:
1. New ballparks which emphasized hitting, but that didn’t really begin until 1970 or so
2. Expansion, but that started slowly in the early 60s, and most expansion effects only last a year or so (or so said Bill James)
3. Changes in strategy to emphasize hitting
4. The mini Dead Ball Era of approximately 1962-1968
There’s probably more, but the strikeout is here to stay. I would question whether these strikeouts are “bad” in the manner that old baseball purists (i.e., anyone who played baseball prior to today’s players) believe. I’m not sure that is so cut-and-dried.

I show this next chart for illustration only—it’s the historical trends for batting average, on-base percentage, slugging and batting average on balls in play (BABIP):

There is a slow but steady rise in BABIP from approximately .270 in 1950 to around .300 today, an increase of over 10%. Of course, this doesn’t factor in strikeouts, so increases in strikeouts won’t affect it, but it does show the value of putting a ball in play. This is what the old-time baseball player would say—“Put it in play and see what happens.” Generally speaking, I would agree with this approach, but something else has happened that will be apparent when the BABIP and OBP lines are taken away:

These are the differences between hitter’s OBP and batting average and slugging and batting average. Historically, the average player has an OBP about 60-70 points higher than his batting average. The .270 hitter would have an OBP of around .330-.340, and variations in one direction or the other were noteworthy. This has remained remarkably unchanged in over 100 years of baseball history, which is stunning. The other line, the difference between the slugging percent and batting average, begins to shed light as to why strikeouts are more common these days—quite simply, the payoff is greater. The difference in slugging percent, or in other words, the value of the balls hit (more extra-base hits than singles), while down from its (performance-enhanced) peak of 2000, is still near historical highs.

One of the take-home points from the Wall Street Journal article was that power pitching is becoming more prevalent and that teams are willing to pay for it. This very well could be true, since runs per game are down and have been going down for the past five years:

But is it the power pitching or the increase in strikeouts that is causing this decrease? Or is it a reflection of the cleaning out of the performance-enhanced hitting? It’s probably both, as well as other factors—the danger is to over-emphasize one.