Searching for BB/9 Decline

As promised, this is part II of a post I wrote about last week about how we can utilize sabermetrics-specifically looking at plate discipline data-to identify pitchers who could be useful to your fantasy team in 2014. Last week I used a helpful tool from fangraphs focused on analyzing various pitching statistics to see which are predictive of future success for K/9 rates. Today, the focus is how we can use these same pitching statistics to look at predicting pitchers' BB/9 rates.

While the value of the strikeout is obvious for fantasy purposes-gains in ERA, WHIP, Ks, and a better chance of Wins-one of the other factors that is just as important for pitchers is the ability to limit walks. Having control (the ability to throw strikes) and command (hitting the target that you want with a given pitch, regardless of whether or not it is in the strike zone or not), can be just as important as the actual velocity and strikeout potential a pitcher has. One has to look no further than new Hall of Famer Greg Maddox who did not have a single pitch over 87 MPH and a career 6.06 K%, but who's impeccable control (1.8 career BB% ratio) led to an unbelievable 22-year career in the majors. At any rate, for fantasy purposes, the fewer walks a pitcher gives up the fewer men on base, the better the WHIP, ERA, which leads to a greater possibility for quality starts and wins.

As in our last study, I looked through all the data for pitchers from 2007-13 with an IP minimum of 30 (max. 1000). Specifically I was looking for pitching statistics that had a medium to strong correlations (r values between 0.3 and 1.0 or -0.3 and -1.0) to see if there was any predictive value for and increase in BB/9 rate the following year. This is not a new concept, it's been well documented already, but there's nothing wrong with reviewing this method just to make sure we haven't overlooked anything.

Here are the stats that had a medium or strong correlation in predicting future BB-rates:

As you can see, we do not have much to go on here. Unlike the various stats that correlate well with K/9, the best we can do here is say that of all the pitching statistics that we watch currently only F-Swing% (the ability to throw first-pitch strikes) has a significant correlation in predicting walk rates. Even then a -.439 value is not considered a strong correlation even though it is significant. At most, then, we know that an increase in throwing first-pitch strikes more often than not has something to do with indicating a pitcher's ability in the future to limit walks. Not a strong endorsement, I know.

So, let's see what pitchers had the largest increase and decrease in F-Swing% from 2012-13 (min. 130 innings pitched):

From the results above we can conclude that, for the pitchers who's F-Swing% went up it's quite possible that this year's BB/9 rate could be headed down in 2014. Likewise, those pitchers who saw a decrease in their first-pitch strike percentage may be watching their BB/9 increase this year. I'd be keeping a close eye on these pitchers if I owned them or are thinking about drafting them this year. More walks means more men on base, which leads to more runs scored, higher WHIPs, and ultimately less quality starts and wins. Likewise, if I'm looking to improve my rotation's peripherals I'd be looking at some F-Strike% surgers after the first few months of the season commence. While it's certainly no slam dunk in predicting BB/9 rate decline, looking at fantasy pitchers from a F-Strike% perspective will at least give you a starting point. Furthermore, as a fantasy manager, you don't have to wait for the "experts" to come out with articles to get the jump on your league mates in discovering the next pitching gem.