Library Update: K% and BB%
It’s not the most glamorous update to the FanGraphs Library, but we’re not really a flashy establishment. Today the entry on strikeout and walk rate (K% and BB%) for hitters got an update.
If you’re a seasoned sabermetric veteran, this probably isn’t going to provide a lot of new information, but the Library is meant to flatten the cost of acquiring information for everyone and there are plenty of new readers every week who might not know the basic rules of thumb associated with some of the more common stats. It’s not hard to guess what BB% means in a basic sense, but understanding how to use it to infer something about a player’s approach is important.
So if you’re new to site and have questions about K% and BB%, feel free to ask them in the comments. And as always, if you have sabermetric or FanGraphs related questions, get in touch on Twitter @NeilWeinberg44 or stop by out weekly chats designed to answer these types of questions at 3pm eastern on Wednesdays.
Neil Weinberg is the Site Educator at FanGraphs and can be found writing enthusiastically about the Detroit Tigers at New English D. Follow and interact with him on Twitter @NeilWeinberg44.
A couple questions/suggestions:
1. Fangraphs displays BB% and K% but no HR% (only HR/9). Is there any possibility of having HR/PA (or HR%) instead of or in addition to HR/9 and have it displayed on hitter pages as well as pitchers? In my mind, it’s helpful to see what percentage of plate appearances end in one of the three true outcomes, with the leftover percentage being balls in play (with some small percentage being HBP I guess). Would love to be able to glance at a player page and see BB%, K%, HR%, and BIP%.
2. This is a bit of a tangent, but is there any impetus for Fangraphs to eliminate stats that use AB in the denominator or at least provide alternate versions calculated with PA instead? So replace AVG and SLG with hits/PA and EXBH/PA. Maybe not worth the trouble, but it just seems a more accurate way to represent the data (similar to how K% was originally K/AB until everyone realized that didn’t make sense and it got switched to K/PA).
I don’t see the point in using a quotient of hits or extra base hits divided by plate appearances. That metric would inflate the “value” of a player who never walks and punish the player who walks a lot.
In 2004, Barry Bonds had a H/PA “average” of .219 in 617 plate appearances. His extra base hits/PA was .122 in 534 plate appearances. Meanwhile Aaron Rowland had a H/PA “average” of .283 and an EXBH/PA of .120.
Even a deranged lunatic would not think that Aaron Rowland was a more valuable hitter than Barry Bonds in 2004. So why would fangraphs include a metric that would give support to a false conclusion?
Correction: Rowland had 534 PA and Bonds had 617.
Sorry, I was thinking extra bases/PA, not extra base hits. Just ISO calculated on PAs instead of ABs. Or even just bases/PA.
My guess, and I don’t know for sure is that we don’t do HR% because we would need a good chunk of decimal places to show good variation. Most guys are going to be 0-3%. And AVG/SLG/etc aren’t exactly mean for a per PA scale. Can always do the division on your own to get a sense of the frequency. Not like we can change average, we would have to make a new stat, and that stat wouldn’t be very useful