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— Where BTF's Members Investigate the Grand Old Game
Monday, June 11, 2001
Don’t worry. Voros isn’t coming clean about a hyperactive deterioration of his psyche. Not yet at least. Instead he’s written a little about Steve Trachsel’s trip to the minors.
It must have all sounded very convincing to Steve Trachsel. “This is exactly the same idea we had with Bobby (Jones) last year,” opined Steve Phillips, “to send him down and get him back on track.” All Trachsel had to was to accept the assignment to the minors and the Mets would “fix” Trachsel’s problems the same way they did with Bobby Jones. And they had proof too. Jones was 1-3 with a 10.19 ERA before his demotion last year, and 10-3 with a 3.69 ERA after. Clearly the demotion had achieved its desired result.
And so another chapter in the annals of Post Hoc reasoning had been added. At times, it seems that most everybody understands the pitfalls of “after this, therefore because of this reasoning.” After all, if you drop your keys and find a dollar bill on the sidewalk, you don’t spend the rest of the day walking down the street dropping your keys every three seconds. However, there is a special case of this reasoning that causes many people problems.
The principle of regression is a standard mathematical concept that has been extended to elementary logic. Simplistically, the idea is that when two things are imperfectly related (like past player performance and future player performance), extreme values on one end match up with less extreme values on the other. We see this in baseball very often and usually think very little of it. For example, until recently very few players who hit 50 homers in one season, hit 50 again the next. So that even though George Foster hit 52 Homers in 1977, while because of that display we’d expect him to hit for power again, he shouldn’t have been expected to hit 50 again in 1978. The Chicago White Sox of 2000 and the White Sox of 2001 are another good example.
In the Mets example, we lack a key piece of information in the case of Bobby Jones and how it relates to Trachsel’s situation. What we lack is the knowledge of what would have happened if Jones hadn’t been sent down. The possibility exists that he would have improved anyway. In fact, it was a probability when you consider Jones previous performances and the principle of regression. As in Trachsel’s case, Jones had an established level of ability that made his poor performance in 2000 qualify as an extreme departure from his previous performances. Isn’t it reasonable to assume that Jones would have improved even if the Mets hadn’t done anything? Aren’t there dozens upon dozens of cases of that exact thing happening? Even if you won’t go that far, doesn’t that possibility at least exist? Why should we assume that being demoted had anything to do with the turnaround.
You know, I could stand here and perform an ancient tribal dance to summon the spirit of Dave Bancroft and have it breathe life into the bat of Royce Clayton. Then, when Clayton hits considerably better afterward than he had beforehand, I can declare the ritual a success. I realize nobody will believe me, but if my results are no less remarkable than those that Steve Phillips has achieved, why are his methods “proven” and mine absurd?
And that lies at the heart of what is known as the “regressive fallacy.” We as humans over the centuries have observed the principle that objects in motion tend to stay in motion, and have developed habits and techniques for anticipating and predicting future events. These generally valid techniques sometimes lead us astray when analyzing out of the ordinary events. Therefore, when Troy Glaus hits 47 Homers at 23 years old, people consider his current less ambitious pace (17 homers in 60 games) a “disappointment.” If he hits 47 at 23 years old, he should hit 49 at 24, 51 at 25, 54 at 26 and 58 homers at 27 years old, right? Well, of course not. The list of 23 year olds who hit that many homers is woefully small and none of them hit as many the following year so the expectation that Glaus would do so is unfounded.
This misunderstanding of regression is at the heart of many questionable beliefs in baseball. The belief in the supreme power of “team chemistry” is reinforced when a team playing unexpected well adds a new player and then “suddenly” starts playing worse. The player must have disrupted the team’s “chemistry.” A struggling player gets moved to a new spot in the batting order and “poof” he starts hitting again. It must be the new spot. A team losing more games than expected fires its manager, then the team begins playing better for the new guy. Must have “woken them up.” It isn’t to say any of those explanations are necessarily “wrong,” just that they aren’t are as clear cut as they would appear, nor are the explanations necessary to explain what happened.
Just once I’d like to hear Chip Caray say: “Rondell White’s 3 for 4 today. You know, Jeff Pentland the Cubs’ hitting coach is trying to get Rondell to relax his forearms at the point of impact in order to give him a more fluid stroke through the zone. While Rondell has really hit the ball well today, it seems to me that since Rondell’s been a career .290 hitter over several seasons, he was gonna start hitting better than .230 regardless of what Pentland had to say.”
But hey, what do Cubs fans care? As long as it works, why knock it? Right?
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