I was originally going to start another thread about how high scoring NBA has been lately, but it looks like we have that covered already. From time to time, I see something interesting on Twitter but the 140 character limit on that site makes it impossible to discuss. A few days ago, I was discussing the correlation of advanced stats in MLB with @msonichdrhass (who is a great follow on Twitter). He was explaining that variation in hitter HR/FB% can be explained by three factors. They are: Hard hit , K, and WFA/C (runs created per 100 fastballs seen). He had something even more interesting to say about pitcher HR/FB%.
This is copied from @msonichdrhass Twitter account:
For pitchers HR/FB% is (almost) solely a function of Hard%. For every increase of 10% in Hard% HR/FB% goes up (on average) 3.85%. Round up to 4%, if you want. So, if a P allows 25% Hard%, his HR/FB% should be ~10%….this remains consistent over the years, with the ratio moving ~1% in either direction. This is both a simple and powerful way of looking at HR/FB%. The maxim is that the HR/FB% regresses to 10% for a P. But it appears that Hard% is actually driving the analysis. If a P’s Hard% is below 25% or so, his “low” HR/FB% isn’t “lucky”—-unless, of course, his Hard% is “lucky” itself. So, bottom line, if you want to help predict a P’s future HR/FB%, look at a P’s Hard% relative to his HR/FB%, not his HR/FB% relative to 10%.
Ok, for all of you who didn’t get that. What he is saying is that you can possibly predict when a pitcher’s HR/FB% will regress to the mean simply by looking at his hard Hit%. For example, if a pitcher is allowing HR/FB of 17% but his Hard Hit% isn’t 45% or higher we can expect some regression coming. He should eventually get back to around league average of 10% unless we expect his Hard% to remain high. On the other hand, if a pitcher is allowing a Hard Hit% of 45% but somehow his HR/FB% is only 9% we can expect that the HRs will be coming.
What are your thoughts on this? I’ll see if I can get the original author to join this thread. What other stats do you look at in MLB and what do you compare them to?