Clay Buchholz is a very good pitcher, at least if you give any weight to ERA. Since he debuted in 2007, his 121 ERA+ ranks 19th in baseball, just behind David Price, and a shade ahead of teammate Jon Lester. Over the last four seasons, he's pitched to a 135 ERA+, which is the 7th-best mark in baseball, ahead of pitchers such as Felix Hernandez, Stephen Strasburg, Yu Darvish, and Price.
Despite general excellence at preventing runs, Buchholz has had some up and down years. Following an August call-up in 2007, he threw a no-hitter in his second career game. The next season he posted a 6.75 ERA in 76.0 innings. While 2012 saw him throw a career-high 189.1 innings, he had a pedestrian 92 ERA+.
Though he threw only 108.1 innings in 2013, Buchholz compiled 5.0 RA-9 WAR, the 15th-best mark in the majors. On some level, it was one of the best seasons in baseball history. There are only seven other seasons in which a starting pitcher threw 100 innings and compiled an ERA+ better than 230. Four of them were authored by Pedro Martinez or Greg Maddux.
By way of comparison, Clayton Kershaw had a 194 ERA+ in 2013, albeit in more than twice as many innings. Buchholz did this despite strikeout and walk rates of 23.1 percent and 8.7 percent, which are good marks, but far from elite. Lance Lynn and Tim Lincecum had similar strikeout and walk rates, but posted an ERA+ of 91 and 76, respectively.
Through his seven big league seasons, Buchholz has managed to hold down hits on balls in play. While Red Sox pitchers as a whole have a middle of the road .293 BABIP since 2007, Buchholz has a lower-than-average .278 mark.
He's done this mainly by limiting groundball hits. Batters have hit just .210 on groundballs against Buchholz, far below the major league average. It's realistic to expect Buchholz's BABIP and HR/FB rates to regress from their 2013 marks, but he's beat his FIP and xFIP by a wide margin over a sample of nearly 750 innings and 2,200 balls in play.
The biggest knock on Buchholz, however, is his inability to stay on the field. In six seasons as a starting pitcher, he's thrown enough innings to qualify for the ERA title just twice, and he's averaged only 120 innings per season in that span. Still, Buchholz has averaged 1.9 fWAR and 2.6 RA-9 WAR since 2008.
Conversely, Ricky Nolasco and Edwin Jackson, innings munchers who have received nice contracts in the past two offseasons, have averaged 1.5 RA-9 WAR and 2.4 RA-9 WAR since 2008, while throwing at least 420 more innings than Buchholz.
It would appear, then, that a half-season of Buchholz with a fill-in of precisely replacement-level pitching is more valuable than a full season of the noted FIP underachiever Nolasco or the average Jackson.
Furthermore, pitchers who were durable in the past are not always durable in the future. Based on Jeff Zimmerman's injury data, starting pitchers on average have a 38 percent chance of landing on the disabled list. His 2014 DL predictions see Nolasco and Jackson as relatively low-risk pitchers, with 34 and 33 percent chances of landing on the DL, respectively. Buchholz isn't to be found on this list, as he didn't even throw 120 innings in 2013.
Per ZiPS, Buchholz is projected for 128.2 innings, which is about 50 innings fewer than Nolasco or Jackson. However, he projects for 2.6 WAR, while the aforementioned pitchers project for 1.9 and 2.1 WAR.
If average pitchers with track records of durability were underrated before, they certainly are not anymore. Jackson, who entered 2013 with a career 98 ERA+, received $52 million for his age-29 to 32 seasons. Nolasco, who owns a career 94 ERA+, received $49 million for his age-31 to 34 seasons. Bronson Arroyo was guaranteed $23 million for his age-37 and 38 seasons, and Jason Vargas and his 91 ERA+ were guaranteed $32 million for his age-31 to 34 seasons.
Bronson Arroyo's new contract and past free agent seasons have shown that front offices pay a premium for pitcher durability. Perhaps they shouldn't. Perhaps quality is more important than quantity.
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Chris Moran is a former college baseball player and current law student at Washington University in St. Louis. He's also an assistant baseball coach at Wash U. In addition to Beyond The Box Score, he contributes at Prospect Insider and Gammons Daily. He went to his first baseball game at age two. Follow him on Twitter @hangingslurves