What starting pitcher metrics correlate year to year?

From SABR member Bill Petti at Beyond the Box Score on January 9, 2012:

As a follow up to my previous article on hitting metrics, I wanted to take a look at those pitching metrics that correlate year-to-year. For this installment, I looked at starting pitchers from 2004-2011 with at least 162 innings pitched in year one and year two.

As before, this is just a straightforward correlative analysis–nothing fancy. I took a look at a bevy of metrics (courtesy of the fine, upstanding citizens at FanGraphs), and here are the results:


Pitcher repertoire generally has the highest correlation, year-to-year (Y2Y). The distribution of their pitches (i.e. four-seam fastball, cutter, change up, etc.) shows great consistency from one year to the next. Now, there are potentially coding errors in that data, but the consistency of those statistics reflects what I think is generally known–that once a pitcher makes it to the big leagues as a starter they rarely alter their portfolio of pitches. What they likely alter, more regularly, is speed, sequence, and location. But that’s just a hypothesis, one that can’t be confirmed or rejected with this data.

Moving on.

Outside of repertoire, the highest correlated statistic for starters is the ratio of ground balls to fly balls they throw (GB/FB), followed closely by K%.

Read the full article here: http://www.beyondtheboxscore.com/2012/1/9/2690405/what-starting-pitcher-metrics-correlate-year-to-year

Originally published: January 12, 2012. Last Updated: January 12, 2012.