This afternoon, Mike Petriello put up a really good post on Dallas Keuchel‘s breakout season. Included in that post was a graph plotting every 2014 qualified starter based on two variables: their groundball rate, and their strikeout rate minus their walk rate. Basically, the point of the graph was to show not just how extreme Keuchel’s groundball tendencies have been, but how rare it is for a pitcher to get that many groundballs while also getting strikeouts and limiting walks.

I gave Mike the graph after seeing that he had beaten me to writing a post about Keuchel’s emergence, but that’s not the only interesting data point on the chart, so I’m giving that chart its own post, highlighting some of the more interesting pieces of information that we can gain from plotting pitchers based on those variables.


Before we get to the graph, however, a quick explanation about why the vertical axis is strikeout rate minus walk rate, rather than the traditional K/BB ratio. As others have previously pointed out, K/BB ratio can often be problematic when a pitcher posts a very low number of walks, driving down the denominator and thus creating an artificial sense of distance between similar performances.


http://www.fangraphs.com/blogs/a-graphical-look-at-pitcher-types/