More Velocity and K/9 Charting

After this afternoon’s graph, some of you requested a breakdown by starters and relievers to remove any potential bias among soft-tossing relievers getting inflated strikeout rates due to their situational usage. So, here you go – I broke the group presented in the first graph into greater than 100 IP and less than 100 IP, which is a good enough proxy, and redid the graphs.

Obviously, there are a lot more relievers than starters, but the data is basically the same. As you can see, the slope of the regression line is very similar – there doesn’t appear to be a significant difference between starting and relieving in terms of correlation between fastball velocity and strikeout rate. The r (not squared, which I’ve adjusted based on a couple good comments this afternoon) is .43 for starters and .38 for relievers.

Of course, this is for major league players only. How does velocity interact with strikeout rate in the minors? We’ll look at that tomorrow.