Not Hard To Fathom At All

As Joel Sherman of the New York Post has probably already learned, throwaway statements are usually dangerous because they reflect a surface-level thinking and are usually incorrect. At least, I can only hope this was a throwaway statement and not something Sherman truly believes.

Andy Pettitte is following up the best season of his career with his worst. That is hard to fathom, as well.

When a pitcher has his career year in his eleventh season in the big leagues, that is harder to fathom than the pitcher following up that year with a worse year. The expectation going into this year should have been that Pettitte would come back to earth after posting numbers so much better than his career mean. True, his 1.5 HR/9 innings this season is much worse than any other year of his career, but overall, there is nothing particularly strange about Pettitte's season.

The strange really applies to his 2005 season. During that season, he drastically reduced his BB/9 innings and posted the best mark of his career in that category (1.66 BB/9). He was also much more consistent in his starts last season over this one, with a FLAKE of
.200 in 2005 and .265 in 2006, but that is really immaterial to the point I am trying to prove here, which is that Pettitte's 2005 season is more of an outlier than this 2006 season.

In an effort to prove this, I looked at three of the statistics Andy Pettitte and every other pitcher have the most control over: walk rate, strikeout rate, and home run rate (and for a bonus I looked at his K/BB ratio). Then I found the average and standard deviation of each of those statistics to find out how close his rates in 2005 and 2006 were to the average. Here is what I found.

Pettitte's average walk rate for his career is 2.81 BB/9 with a standard deviation of 0.79. He posted a walk rate of 1.66 BB/9 in 2005 and 3.17 BB/9 in 2006 so while his 2006 walk rate is only one standard deviation away from his career average, his 2005 walk rate is two standard deviations away from the average. Edge goes to his 2006 walk rate for being more in line with his career statistics.

For Pettitte, both his 2005 strikeout rate (6.92 K/9) and 2006 strikeout rate (6.75 K/9) are both within one standard deviation (.90) of his average strikeout rate (6.55 K/9). It must be said that his 2006 strikeout rate is closer to the average so a slight edge goes to the 2006 season for being less unusual for Pettitte.

Another telling statistic of how much of an outlier Pettitte's 2005 year was is his strikeout-to-walk ratio or his K/BB. Again, his 2006 ratio of 2.13 K/BB is one standard deviation (0.95) away from his career average (2.33 K/BB) and his 2005 ratio of 4.17 K/BB is two standard deviations away.

The one statistic I looked at where Pettitte's 2005 season is more in line with his 2006 one is his home run rate. He has a career home run rate of 0.76 HR/9 with a standard deviation of 0.31. In 2005, Pettitte had a 0.69 HR/9, one standard deviation away. This year, Pettitte's home run rate is 1.50 HR/9, worst of his career and a big reason for his mediocre pitching, which is a whopping three standard deviations away from his career average. If Pettitte does not give up another home run for the rest of the season, his home run rate will return to normalcy, but the chances of that happening do not look good.

Overall, though, I can say with confidence that Pettitte's season so far is not hard to fathom at all, contrary to what Joel Sherman believes.