Aaron Harang’s season could probably be filed away in the forgettable folder. Not that it’s as atrocious as, say, Ryan Rowland-Smith’s 2010, but a 5.38 ERA at the back of the rotation for a team that is 11 games below .500 just doesn’t stick in the old memory bank.
Despite an awful ERA, Harang has maintained the best K-to-BB ratio of his career, 4.27. His 64 strikeouts to 15 walks ranks him 14th among starters this season, one spot ahead of a familiar name, Doug Fister. Besides being tall, there are not many other similarities between the two, but pitchers with such good K/BB ratios don’t tend to have ERAs north of 5.00. In fact, since 1980, only five starters have managed a K/BB ratio above 4.00 with an ERA above 5.00 (in at least 70 innings pitched). In that way, Harang’s season is somewhat historic, especially considering he’s pitched 60% of his innings at still-pitcher-friendly SafeCo Field.
Interestingly, Harang’s BABIP, often the driving force behind outlier seasons, is a typical .298. If we are to find the one thing that is keeping Harang from limiting runs against, it’s the long ball. Harang has already given up 14 ding dongs this season with 13 total runners on base. Those 27 runs make up exactly half of his total runs allowed this year. So the question becomes, what’s likely to regress more, Harang’s K/BB ratio in a bad way or his homerun rates in a good way?
There are reasons to believe that the homeruns will regress more quickly. This Baseball Prospectus article from 2011 researched the stabilization rates of various pitching statistics, and found that strikeout rates and walk rates stabilize much, much faster than homerun rates. Strikeouts rates predicted themselves decently in samples spanning only about a month, walk rates in about three months, and homeruns in about three years. The research strongly suggests that Harang’s homerun rates will fall back to earth more so than his K/BB ratio. That is good news.
Some back-of-the-envelope regression calculations suggest a homerun rate closer to 1.0 HR/9 than his current 1.5, 6.75 K/9 and 2.5 BB/9.* That would produce a FIP of about 4.1. Indeed, ZiPS—which does all this fancy regression stuff more rigorously—suggests a similar 4.29 FIP, which isn’t half bad for a fifth starter. Both calculations suggest that Harang is not likely to post a 5.0+ ERA during the remainder of 2013.
Overall, it’s not hard to argue that Harang will continue to serve as an acceptable stopgap for the $1.5M the Mariners are paying him in 2013. Even if you tack on the full $2M buyout when his 2014 option doesn’t vest, it’s not a bad price. However, it’s probably not worth paying him $6M or $7M in 2014 to keep a seat warm. A FIP in the 4.1-to-4.3 range for a 36-year-old guy with no future in the organization isn’t worth a major investment. We saw younger, better pitchers go for that this past offseason.
*Really rough, giving far more weight to this year’s walks than this year’s homeruns.