Buchholz's Record-Setting Season

Clay Buchholz had a magnificent season. His 2.33 ERA was 2nd in the AL and 3rd in MLB.

He benefited from some good luck, more than his rotation mate Jon Lester did, which I'll mention below, but the fact is his ERA was 2.33.Buchholz is the 31st Red Sox starter to finish a season with an ERA as low as 2.33. As you might expect, 24 of those 31 seasons occurred from 1901-1919, aka Ye Olde Deadball Era. Since 1920, Buchholz is only the fourth Boston starter to have such a low ERA:

1944 - Tex Hughson      2.26
1990 - Roger Clemens    1.93
1999 - Pedro Martinez   2.07
2000 - Pedro Martinez   1.74
2002 - Pedro Martinez   2.26
2003 - Pedro Martinez   2.22
2010 - Clay Buchholz    2.33

Buchholz's 187 ERA+ was the best in MLB. (ERA+ takes into account the parks a pitcher pitches in and the context of his league; 100 is average.) Josh Johnson of the Marlins led the National League at 182 and Seattle's Felix Hernandez was third at 174.

Buchholz is the youngest starter in Red Sox history to have an ERA+ over 185 (min. 115 innings and 75% of games as a starter):

                         Age   ERA+
1901 - Cy Young           34   217
1908 - Cy Young           41   195
1936 - Lefty Grove        36   189
1939 - Lefty Grove        39   185
1990 - Roger Clemens      27   213
1999 - Pedro Martinez     27   243
2000 - Pedro Martinez     28   295
2001 - Pedro Martinez     29   190
2002 - Pedro Martinez     30   202
2003 - Pedro Martinez     31   211
2010 - Clay Buchholz      25   187

(Age is as of June 30 of any season.)

In 1912, Smoky Joe Wood was 22 years old and went 34-5, 1.91. However, since this was the Deadball Era, his ERA+ was "only" 179, second in the AL to Walter Johnson's 1.39 ERA / 243 ERA+.

Fangraphs recently referred to Buchholz as a prime example of someone who put up a "shiny ERA without necessarily having the underlying performance to match".

Buchholz did have a fair amount of good luck. He and Lester had identical WHIPs (walks and hits allowed per inning), but Lester's ERA was nearly a full run higher (3.25). Why?

The more I look at their stats, I see that Buchholz and Lester were nearly identical.

         H/9 BB/9  K/9 HR/9  AVG  OBP  SLG BABIP WPA  WAR
Buchholz 7.4  3.5  6.2  0.5 .226 .303 .312 .263  3.6  5.4
Lester   7.2  3.6  9.7  0.6 .220 .303 .325 .291  3.5  5.0

They were both among the top six pitchers in the AL in fewest hits and HR allowed per nine innings. Lester had a clear advantage in strikeouts; his 9.7/9 led the AL, actually.

The key difference is their batting average on balls in play, especially since (because of the difference in strikeouts) 71% of the batters Buchholz faced put the ball in play compared to only 61% for Lester.

The AL average BABIP in 2010 was .294 -- and Boston pitchers came in at .295. Buchholz's BABIP was the third lowest in the AL; Lester was 24th. However, pitchers generally have little control over their BABIP*, so someone with a very low or very high BABIP can be expected to regress to the mean the following season. (Which might bode well in 2011 for John ".320 BABIP" Lackey. ... Maybe.)

* In 1999, Pedro had one of the greatest pitching seasons of all time -- yet he had a .325 BABIP! In 2000, he was even better -- and his BABIP went way down to .237. In 2001, it was back up to .310.

Also, Buchholz's stats with men on base and RATS were much better than Lester's.

Bases Empty

           AVG   OBP   SLG  BABIP
Buchholz  .243  .315  .350   .288
Lester    .206  .294  .286   .298

Men On Base

           AVG   OBP   SLG  BABIP
Buchholz  .202  .287  .256   .230
Lester    .240  .316  .379   .284

RATS (Runners At Third and/or Second)

           AVG   OBP   SLG  BABIP
Buchholz  .161  .273  .212   .188
Lester    .225  .314  .382   .258

Fielding Independent Pitching removes fielding and the vagaries of BABIP from consideration and measures the things for which a pitcher is specifically responsible. While not perfect, it is considered to be a better measure than ERA of how well a pitcher actually did -- presenting his performance as a context-neutral ERAesque number.

Buchholz's FIP in 2010 was 3.62, while Lester's was 3.14 (6th best in the AL). Again, I assume the difference is Lester's higher strikeout rate, since allowing fewer balls in play will mean fewer chances for hits to fall in.

All of this is not meant to denigrate Buchholz's 2010 performance. On my BBA ballot, which I will be posting about later as the full results are announced, I had him 2nd for the Walter Johnson Award (the BBA's version of the Cy Young Award). But if Buchholz's 2011 ERA shoots up to 3.50, he may still be pitching nearly as effectively as he did this year.