The Dangers of On-Base Percentage

With no game to mismanage last night, Tony LaRussa instead told reporters that he was going to go see Moneyball. He might have been joking, since he’s clearly not a fan of the concepts associated with the book. A bit later in the same interview, in fact, he said this:

“On-base percentage is one of the most dangerous concepts of the last seven, eight years, because it forces some executives and coaches and players to think that it’s all about getting on base by drawing walks. And the fact is that the guys that have the best on-base percentage are really dangerous hitters whenever they get a pitch in the strike zone.

“So if the pitcher knows that and the catcher knows that, they work the edges, and pretty soon it’s 2-and-1, 2-and-1 rather than 0-and-1 all the time.

“You watch your productive hitters in the big leagues, and they get a chance to drive in a run, they look for the first good strike, and the better the pitching, especially this time of the year, you get that first strike, that may be the last one that you get to see. So you’d better be ready to swing early. It’s not sitting up there and taking strike one, strike two so that you can work the count.’’

Let’s put aside the fact that the point of Moneyball was not “OBP=Good” and just address LaRussa’s contention directly – does the philosophy of taking pitches cause hitters to perform worse?

There’s a bit of a chicken and an egg problem here. As LaRussa notes, pitchers do not throw the same pitches to every batter, and the inherent ability of a hitter to drive the baseball will influence how many good pitches to hit he sees. If a guy is taking a lot of pitches, drawing walks, and getting into good hitting counts, we can’t say for certain whether he was simply not being thrown any good pitches to hit or whether he was working himself into those counts through a discerning eye at the plate. Does the batter get into a 2-1 count because he doesn’t swing at anything or because the pitcher won’t give him anything to swing at?

It’s different for every hitter, certainly, but we can look at the data on player’s swing rates and the fear they should be instilling into opposing pitchers.

Thanks to our awesome new Custom Reports feature on the leaderboard, I simply created one page where you could see each player’s ISO, wOBA, Swing%, and Zone% side by side. If you sort by Zone%, you’ll see which players saw the fewest pitches in the strike zone.

At the bottom of the list, we find Prince Fielder, Ryan Howard, and Mike Stanton, which makes sense – they’re all pretty scary hitters who can demolish a mistake in a hurry. At the top of the list, it’s Darwin Barney, Michael Young, Jason Bartlett, Kurt Suzuki, and Juan Pierre – not exactly big home runs guys. It’s self-evident that pitchers will throw more strikes to hitters who don’t scare them.

However, fear isn’t the sole determining factor of what kinds of pitches a hitter is thrown. The correlation between Zone% and ISO is -.47, meaning that the r-squared is just .22 – or, in English, that a player’s power explains just over 1/5th of the variation in frequency of strikes that they are thrown. Again, looking at the list, this is apparent – while Fielder, Howard, and Stanton are scary hitters, they’re also scary hitters who swing the bat a lot.

The relationship between a hitter’s Zone% and his Swing% is even more apparent when you look at the next three guys on the low-strike list – Freddie Freeman, Vladimir Guerrero, and Josh Hamilton. These guys all swung the bat more than 50% of the time, and pitchers are no doubt exploiting their aggressive approaches by feeding them pitches off the plate. They’ve shown a historical willingness to swing at such pitches, so it doesn’t make much sense for pitchers to attack the zone against guys who will chase pitches no matter where they are thrown.

By sorting Swing%, we can actually see this even more clearly. The three regulars who swung the bat the least often in 2011 were Bobby Abreu, Brett Gardner, and Jamey Carroll. These guys combined to hit 15 home runs last year, and are no real power threat whatsoever. And yet, they didn’t see a dramatic increase in pitches in the strike zone. Abreu was thrown 43.5% strikes, actually below the league average of 45.3%. Gardner and Carroll were thrown 48.0% and 48.6% respectively, a bit above average, but not so dramatically that it eliminated their ability to draw walks and get on base.

If LaRussa’s contention was right, and that the quality of pitches seen was dictated simply by the amount of intimidation a batter could inflict on the opposing pitcher, guys like Gardner and Carroll would have Zone% that were off the charts. The fact that the spread in Zone% between power hitters and slap hitters is relatively small indicates that there’s a lot more going on than simple fear on the mound driving what kind of pitches a hitter sees.

The prevalent existence of high walk, low power guys essentially shatters the idea that bases on balls are solely a product of a pitcher’s unwillingness to throw strikes because they’re scared. Even at the Major League level, a lot of pitchers fail to throw strikes because they’re simply not able to command their pitches well enough to pound the zone with regularity. Even in this series, we’ve seen high quality pitchers just lose their ability to throw strikes, issuing walks to inferior hitters in situations where the last thing the team needs is a baserunner.

Patient hitters can absolutely take advantage of this flaw in order to get themselves into better hitters counts, even if they lack intimidating power. A patient approach at the plate may come with a byproduct of taking strikes from time to time, but it will more often involve hitters not swinging at pitches out of the strike zone, and the net gain is significantly positive.

There’s just no evidence to support the idea that batters being selective in what they swing at is “dangerous” or is producing sub-optimal results relative to a more aggressive approach at the plate. Good hitters swing at strikes, bad hitters swing at balls. There are a few notable exceptions, but if you want to have a good line-up, you’ll do a lot better collecting “Moneyball” type of hitters than going the other direction.

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Dave is the Managing Editor of FanGraphs.

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Bill Petti

Good stuff, Dave.

I took a look at this very topic the other day. If anything, the relationship between working a pitcher more and performance is positive, if not terribly robust:

Now, this just looked at P/PA as it relates to performance, but it reaches pretty much the same conclusion.