Spring Training and Strikeouts
First off: Welcome back baseball! Today is the first day of the Cactus and Grapefruit leagues which means we get our first taste of tangible 2008 baseball stats, sort of.
I’m a big proponent of taking spring training stats with a grain of salt. Spring training is the time to examine opening day position battles and try and get a glimpse of which players are healthy. But can you gain any insight into how a player’s regular season will be based on how he performs in spring training?
For this particular exercise, let’s look at pitcher’s strikeout rates (K/9). If you look at the correlation between K/9 in 2006 and 2007, you get an R^2 of about .58, which is pretty strong correlation. When you look at the correlation between spring training 2007 and the 2007 regular season, the R^2 drops to .32. So as a whole, 2006 is a much better indicator of a player’s 2007 strikeout rate than spring training.
The most innings a pitcher will pitch in spring training is roughly 25, so we’re looking at a fairly small sample size which is problematic. But what if a pitcher during spring training has shown extraordinary improvement in his strikeout ability?
For instance, Rafael Betancourt’s K/9 in 2006 was 7.6 and in spring training it jumped to an impressive 12.5. His was the biggest jump from 2006 to spring training and he did indeed show improvement during the 2007 regular season with a K/9 of 9.1.
Of the 161 pitchers sampled, whichever direction their K/9 moved in during spring training when compared with the 2006 season, 63% of them had their K/9 move in that same direction when comparing 2006 with the 2007 season. The correlation of the difference between 2006 and spring training and the difference between 2006 and 2007 had an R^2 of .19.
So there is something there, but it’s not anything you want to bet the bank on. By no means would I suggest looking at a player’s huge K/9 jump in spring training and thinking that it would definitely translate into 2008 success. Oh, and while I’m at it, spring training ERA should not just be taken with a grain of salt; it should be ignored completely.
As a side note, we’ll be carrying 2008 spring training stats starting soon for your own amusement.
David Appelman is the creator of FanGraphs.
What about when factoring in walks? Seems if there is a huge jump in command, as Shandler has labeled it, in spring training then the probability of improvement during the season is even higher. Last year, I remember Volquez was one with a great k/bb ratio in spring training. His control seemed to get progressively worse as the season went on but he was a surprise to most people.