The decline in OBP

A common misconception is that Billy Beane discovered on-base percentage, which was subsequently leaked to the world by Michael Lewis in his best-selling book Moneyball. In fact, the importance of OBP goes back at least to Earl Weaver and his famous dictate "The key to winning baseball games is pitching, fundamentals, and three run homers," which recognized the importance of baserunners for power hitters like Boog Powell and Frank Robinson to drive in. Dripping sarcasm added. In 2015, we might take for granted the importance of OBP so much so that we don't even discuss it.

This chart shows the relationship between batting average and OBP since 1901:

In this time period, the gap between OBP and average has been around 70 points, and this chart shows the changes in this gap:

The gap between OBP and average has been decreasing since around 2009, just after the decrease in offense that began in 2006. I don't want to overstate a difference that amounts to only around five to seven points, but it is something to note in an era that professes to recognize the importance of getting hitters on base.

A primary cause is that players are taking fewer walks:

Walks have decreased by around one per game just since 2000. Lower batting averages coupled with the decreased tendency to take walks will definitely yield fewer runs scored. This is happening at the same time that hitters are taking more pitches per at-bat, so plate discipline isn't an issue.

This chart shows the percentage of players with at least 300 plate appearances and an OBP below .300:

In 2014 there were 263 players with at least 300 PA, and of those, 66 had an OBP of .300 or lower, just over twenty-five percent of quasi-regular players. This percentage has more than doubled since 2010, which represents a stunning change in plate discipline. In a similar vein, players with an OBP of .350 or higher show a similar dropoff. In an era that professes to acknowledge the importance of reaching base, this is hard to believe.

Who are these players? The poster child is Billy Hamilton of the Reds, who batted .250 with a .292 OBP in 2014. The Reds love his speed at the top of the lineup, and he's a legitimate threat to turn any opportunity to reach base into an extra-base event. Unfortunately, it's the reaching base part that's been difficult, as he struck out 117 times and took only 34 walks in 2014. He was dead last among all leadoff hitters with at least 300 PA in OBP by ten points (next-worst was Desmond Jennings at .301). His defense was stellar, and his base stealing should only improve with experience, but his batting profile screams number eight hitter as opposed to leadoff.

The confounding aspect of these players is that over half of them had ten or fewer home runs in 2014. They're not legitimate power threats but have hitting profiles suggesting they're swinging for the fences. Players like Roughned Odor, Chris Owings and Jean Segura add value when they get on base and allow middle-of-the-order hitters to drive them in. It's a trend that confuses me greatly since it seems so obvious--it's certainly not as black-and-white as I'm stating it, but players like Hamilton and Segura would aid their teams more by taking more walks, especially when they don't have the pop in their bats to justify high strikeout rates.

This chart shows a very dubious achievement, players in 2014 with an OBP less than .300 and a spread between their OBP and average of less than forty points. In other words, these are the players who didn't hit for average and didn't take walks either:

Name	Tm	BA	OBP
Jonathan Schoop	Orioles	.209	.244
Wilson Ramos	Nationals	.267	.299
A.J. Pierzynski	2 Teams	.251	.288
Salvador Perez	Royals	.260	.289
Brayan Pena	Reds	.253	.291
Chris Owings	Diamondbacks	.261	.300
Rougned Odor	Rangers	.259	.297
Junior Lake	Cubs	.211	.246
James Jones	Mariners	.250	.278
Chris Johnson	Braves	.263	.292
Everth Cabrera	Padres	.232	.272
Brandon Barnes	Rockies	.257	.293
Mike Aviles	Indians	.247	.273

There are many stories in this list--catchers whose other skills are considered so important as to overshadow their ability to get on base (or just had off years), players like Junior Lake, James Jones and Chris Johnson who are hanging on to big-league jobs by their fingernails, and folks like Everth Cabrera who may have just had a bad year.

Baseball is nothing if not an ever-changing cat-and-mouse game between offense and defense, aided by any number of outside agencies such as performance-enhancing drugs, new stadiums, and expansion as well as improvements in player development. Runs have been decreasing since 2006, down from 4.86 per game to 4.07 in 2014, around a twenty percent decrease in less than ten years and haven't been this low in a full season since 1976.

This could all just be a statistical blip, a period where pitchers just happened to have an edge on hitters for any number of reasons that can't be readily explained. Earl Weaver would have a hard time managing today's game, because the three-run homer can't occur without two runners on base. I have no doubt managers and GMs are attempting to address this trend, because teams can't score without getting on base.

It's one thing to identify an issue, quite another to solve it--it doesn't take much for me to type "Billy Hamilton needs to cut down on his strikeouts and take more walks." I know this because I'm pretty sure I've written it at least three times in the past year. For some reason, hitters are having a more difficult time getting hits and taking a walk, and that's not a good combination going forward. OBP is down over thirty points since 2000, which translates to almost 6,000 fewer times reaching base. I strongly suspect it's in the hitters' court to fix, since until they show patience and a willingness to take a walk, pitchers will just keep feeding them stuff low and away. And if the league doesn't help them out by shrinking the strike zone, these trends will only continue.

All data from Baseball-Reference. Any mistakes in gathering and processing the data are the author's.

Scott Lindholm lives in Davenport, IA. Follow him on Twitter @ScottLindholm.