A week ago I looked at the probability of Chipper Jones hitting .400 for the season based on what he already accomplished, and posted a spreadsheet for future calculations. Last Thursday the probability stood at .000095. Chipper is still well over .400 at .418. He went 9 for 18 on the week with five walks. He’s lowered his expected AB for the season to 562 from 585. The fewer AB Chipper gets, the easier it is for him to hit .400. That raises the probability of him hitting 400 for the season to .0004, or about four times higher than last week.
Update: Chipper singled in his first at bat today, raising his batting average to .422.
Update: Jones now 2 for 2 and batting .425. The Braves lead the Brewers 1-0 in the fourth.
Interesting.
This sort of calculation is very dependent on your assumption for his “true” batting average. In your spreadsheet you are using .309, based on his career average entering the season, I suppose. I’m not sure how relevant Chipper’s .265 batting average back in 1995 really is to this equation. I am NOT suggesting that this is the right way to do it (in fact, I’ll be the first to admit that this is a pretty biased approach), but if you were to use as Chipper’s “true” hit rate his batting average since the beginning of 2006 (.346 – 383/1,108), with the understanding that he’s a different hitter since then and pre-2006 numbers are no longer relevant, then the likelihood that he reaches .400 this year increases nine-fold to 3.5% (and that’s already somewhat significant). Similarly, if you were to assume that since the beginning of the 2007 season he’s improved as a hitter and used as his “true” hit rate his batting average since then, his likelihood of reaching .400 this season is just over 10%. Now we’re getting somewhere.
Finally, just for fun, if you were to assume that the 2008 version is the real Chipper and a .418 batting average reflects his true level of ability, the likelihood that he would hit at least .400 this year is 86.3%!
Aryeh