Derek Jeter and the myth of “On pace for”

From Jordan Ellenberg’s How Not to Be Wrong: The Power of Mathematical Thinking (a fantastic book for analysts):

Derek Jeter, when bugged about being on pace to break Pete Rose’s career hit record, told the New York Times, “One of the worst phrases in sports is ‘on pace for.’”

What does he mean?

Baseball offers a tremendous opportunity for analysts to understand the importance of statistical thinking in business and life. Take the phrase, “on pace to do ______ [X result].” You’ll hear this in ball clubs and boardrooms alike.

The issue here is that observations can sometimes be extreme. A player can open the season with a home run streak. Launch sales might blow away expectations. However, as more observations are recorded, values will “revert” to the mean (a player or product’s overall average). This doesn’t mean that the player or product has been “jinxed” by poor performance.

It’s a statistical phenomenon that can trick us into thinking small blips indicate larger trends.