After three consecutive seasons with ERAs under 4.00 in one of baseball’s most unfriendly ballparks to pitchers, perennially underrated pitcher Aaron Harang is currently holding a 5-16 record and a 4.70 ERA leading to many traditionalists passing it off as a terrible season. But what really, if anything, has changed for Harang in 2008 compared to his 2005-7 stretch and is his season really all that bad?
The first such piece of evidence to investigate is the strikeouts since they usually tell us most of the story. From 2005-7, Harang punched out 21.1% of the batters that he faced. That’s down to 19.6% in 2008. Okay, that is a decline, but it’s not much of one, equaling about 15 batters per full season or less than half a batter per start.
Lets move on to free passes. It is usual here to just look at walks, but there are two problems with that. One, it counts intentional walks which any measurement will tell you are just not nowhere near as costly and in terms of evaluating a pitcher’s control should just ignored. Secondly, it ignores hit batters, an egregious omission since hitting a batter is almost always indicative of poor control. Over the prior three year span, Harang let just under 6% of batters reach base freely while this year it has moved to just a shade over 6%, a really minuscule difference.
What is mostly responsible for Harang’s suffering this season are the fly balls and the home runs. Harang’s groundball rate has plunged to its lowest rate since 2002 back when he was with the Athletics. In addition to that, Harangs percentage of home runs allowed per fly ball is also at an all time high, not a good thing to miss with a newfound increase in fly balls. In fact, if you took Harang’s home run per batter faced rate from 2005-7 and applied it to 2008, you should shave 11 home runs off his season which all by itself would be enough to bring his ERA down under the 4.00 mark assuming the standard 1.4 runs per home run.
It seems likely that Harang’s groundballs and home runs per fly would regress a bit toward his career norms next season, making him more than a decent buy low candidate but there is another ominous sign. Paired with the decline strikeout rate is a rather abrupt fall in swinging strikes generated, a key driver of strikeouts going forward for pitchers. I would expect Harang to get his home runs allowed back under a bit more control in 2009, but pay careful attention to those strikeouts to see if they fall off any more.
Matthew Carruth is a software engineer who has been fascinated with baseball statistics since age five. When not dissecting baseball, he is watching hockey or playing soccer.