I've been on the Braves blogosphere for quite a few years now, and there are few writers I respect more than Peter Hjort. We go back a long time on Mac Thomason's Braves Journal, and he and I both started blogging on our own around the same time. He runs Capitol Avenue Club, the best sabermetric Braves blog on the web. We're trying out a content-sharing agreement between our two blogs, to see if we can both benefit. Let us know what you think!
Chipper Jones is a Braves legend. Whenever he hangs up the spikes, his number is going to be retired, he'll immediately go into the Braves hall of fame, and he'll be headed for the Baseball Hall of Fame shortly there after. It's a blessing to have such a gifted player on your team, period--much less for sixteen years--and watching Chipper develop and rake over the past two decades has been a delight for Braves fans, team mates, executives, and owners alike.
However, stated plainly, Chipper is getting old. 2010 will be his age 38 season and players don't hit forever. After Chipper suffered what was probably the worst season of his career since 1995 (his rookie year) in 2009, it's appropriate to question how much Chipper has left in the tank. In order to come up with a good answer as to what to expect from Chipper going forward, it's important to understand where he's been.
Chipper's success has been primarily a product of his balanced offensive production. He's the rare type of player that hits for a high average, walks a lot, and hits for power. He's one of 14 players to play 2,000 career games and post a batting average of at least .300, an on base average of at least .400, and a slugging average of at least .500*. The kind of offensive balance and production Chipper has been able to sustain over the years is beyond remarkable, it's legendary. However, said balance in production leads to complications when attempting to isolate, quantify, and predict the various offensive attributes.
Rather than trying to separate the components of on base average or slugging average, I prefer to start from scratch and examine this as a problem of primary and secondary production. The metrics I've chosen to represent the two components are, naturally, batting average and secondary average. Quite simply, how much a player produces via hit and how much a player produces via anything other than a hit--on a rate basis in both cases. The linear combination of these two metrics yields a metric called APS (average plus secondary). Think of APS like OPS, only it doesn't double-count for hits (so the totals are going to be lower) and isn't a pile of mathematical gibberish. The formula for APS is (TB+BB+SB-CS)/AB.
Chipper Jones owns a career .307 batting average and a career .411 secondary average, good for a .718 APS. For perspective's sake, last year the average NL 3B posted a .261 batting average and a .271 secondary average (.532 APS). In 2009, however, Chipper's APS experienced a sharp decline. His .643 mark still rated about 110 points above league average for an NL 3B, but it rates 74 points below his career average and 145 points below his 2008 mark of .788 (the second highest of his career). But, looking at one year trends isn't particularly productive and I could explain this until I'm blue in the face, but, instead, I'd like to present the information visually:
Click to see some spectacular charts, and even more analysis...
As you can see, in 2009 his secondary average declined for the third year in a row and it could be said that his SecA has (basically) been steadily declining since 2005. This is consistent with an aging player, a steady decline in peripherals. This is normal, this is to be expected, and if this were the end of the story, we wouldn't be having this conversation and there would be no need for me to write this article. However, most of Chipper's drop in production can be attributed to a 100 point decline in batting average from 2008, not his comparatively measly 45 point drop in secondary average.
Batting Average is a function of two things. One is how frequently the player puts the ball in play. We can quantify this by examining strikeout rates. In an at-bat (not a plate appearance), a player will either strike out, put the ball in play, hit a home run, or sacrifice. Sacrifices and home runs happen so infrequently--even the best power hitters in the game usually don't hit home runs in even ten per cent of their at bats--that strikeout percentage gives us an excellent idea of how well a player puts the ball in play. The other thing that batting average is a function of is how frequently the balls put in play fall for hits. We can quantify this with batting average on balls in play. The formula for batting average on balls in play is (H-HR)/(AB-HR-K+SF).
Chipper has struck out in 15.74 per cent of his at bats throughout his career. In 2009 Chipper struck out in 18.24 per cent of his at bats. A 2.5 per cent increase in strikeouts is only a tad bit over one standard deviation away from Chipper's career average and once we regress for aging, his strikeout numbers are so close to where we'd expect them to be that it's something we can file in our drawer and forget about. In other words, Chipper struck out a bit more in 2009, but there's not enough evidence to say he's fundamentally more strikeout prone than he was a year ago. Furthermore, there's absolutely no way that a 2.5 per cent increase in strikeouts is solely responsible for a 100 point drop in batting average. Yes, it's responsible for some of the batting average decline, but, like I said it doesn't tell the whole story.
Let's take a look at Chipper's strikeout rates over time and his strikeout rates vs. batting average:
What tells us that Chipper's decline in batting average can't be explained entirely by the modest increase in strikeouts is the error on 2009's data point, visualized with a thick red line in the following graph (a modified version of the previous one):
We can't ignore the attenuation bias we get from running a regression on a noisy independent variable (batting average, which fluctuates a great deal more than a player's fundamental hitting ability), but it's clear to me that something else is at play here.
The answer is Chipper's batting average on balls in in 2009 was 0.287--30 points lower than his career average. Let's take a look at Chipper's BABIP over time:
I'm now going to pause to again show you a graph of Chipper's batting average over time:
The R^2 of 0.88 indicates a strong correlation and one that is statistically significant even at the n = 16 level. This holds true in all of baseball, not just with Chipper. Observe the same graph for all players, 1995-2008:
I want to stop and make a point before I move on. Strikeouts tell us nothing useful about how often balls put in play fall for hits. A plot of Chipper's batting average on balls in play vs. his strikeout-to-at-bat ratio yields the following:
The R2 of 0.24 indicates a very weak correlation and one that isn't statistically significant at the n = 16 level. Furthermore, take all batters (minimum 300 AB's) from 1995-2008 and we get:
This indicates that there is zero evidence that strikeouts have predictive value with respect to batting average on balls in play. So, the only reason that more strikeouts explain batting average decline is a player who strikes out more puts the ball in play less. It has nothing to do with whether or not the balls put in play fall for hits.
So, if Chipper's 2009 season was characterized by only slight declines in secondary average and strikeout rates but a huge decline in BABIP, it would behoove us to learn a little bit more about what makes a player's BABIP fluctuate.
The answer is more luck, better positioned defenders (aka luck), and entropy (aka luck) than anything else. How hard Chipper hits the ball has something to do with it, too, but there's not a good way to quantify that without adequate Hit F/X data and Chipper's 2009 batted ball peripherals are well within the normal range. So, what can Chipper do to correct this?
The answer is nothing, but that's not necessarily a bad thing. Generally, when a player has a bad year primarily because of BABIP (like Chipper did in 2009), they tend to rebound the following year. The probability of getting that un lucky twice in a row is very small, and therefore, we can expect some BABIP regression in 2010, which should be observed in an increased batting average should he steer clear of the bad luck fairy.
I'm not here to say that Chipper is ageless and none of his '09 struggles can be attributed to aging. That's incorrect, some of them certainly can be. But not all of his decline in production is a product of aging, a sizable chunk of it comes from mostly un avoidable bad luck. Chipper is no more subject to said misfortunes than any other player in baseball, it happens to dozens of players every year. It works both ways, too, sometimes players get extremely lucky with hits on balls in play. Either way, regression is generally to be expected the following year, whether that's a good or bad thing. In Chipper's case, this is a good thing, and even when we pile a bit more regression due to aging onto Chipper's peripherals, we still come up with something quite a bit better than his 2009 season, every time.
That's not to say he will be more productive in 2010 than he was in 2009, we certainly aren't capable of predicting injuries or rapid deterioration of fundamental skills or another spell of bad luck. The best we can do is come up with a projection that attempts to minimize the standard error--something that Chipper is just as likely to out perform as he is to fail to reach. And since when we do this we get something better than Chipper produced in 2009, he's likely (has a greater than fifty per cent chance) to be a more valuable hitter than he was in 2009.
In closing, I'd like to present a quote from Phil Birnbaum from a recent blog entry called More pitching randomness than just DIPS:
In "The Physics of Baseball," Robert Adair reports that the difference between hitting the ball to center field and hitting the ball foul is 1/100 of a second. No batter is so good that he can always time his swing to .01 seconds. Some batters may be closer to that than others: maybe one batter has an SD of 1/100 of a second, so that he hits the ball fair 2/3 of the time, and another has an SD of 2/100 of a second, so that he hits the ball fair only 38% of the time. Talent and practice and concentration can lower a player's SD, but not to zero.
No matter what, in baseball and in life in general, entropy isn't going away. That's just the way the world we live in works--there's a tendency for things to become more random. On a microscopic level, our bodies expend energy to combat said entropy. In baseball, it's best to understand it and to just live with it, because sometimes, like in the case of Chipper Jones I've presented here, it can be our friend.
Appreciating the understated brilliance of Chipper Jones and the Braves - Joe Posnanski | SI.com ^ up