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Fantasy Baseball: Strikeout Efficiency

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FanGraphs added swinging strike percentage to its repertoire a little bit ago, but only recently has one been able to sort the leaders of the stat. Inspired by this, I decided to do a little number manipulation.

We know that there is a fairly strong positive correlation between swinging strike percentage and strikeouts. So, knowing this, I figured it might be fun to check out which pitchers should be throwing more Ks given his swinging strike percentage, and which should be getting fewer.

I placed both sets of stats (swinging strike% and K/9) in a spreadsheet side by side. The sort of undervalued player we are looking for has a high swinging strike percentage and a low K/9, so subtraction was in order. Because the two rates are on a different scale, I added the two numbers then divided to find out that swinging strike numbers are 1.192 times larger than K/9 in terms of sheer size. So my formula was (SwStr%) – (K/9)(1.192).

I’m calling the resulting number K-Efficiency (apologies if this has been done elsewhere—I’m sure it has I just haven’t seen it—and it stands by another name). The higher the number actually means a lower K-Efficiency, so here are the top 10 leaders of players that "should" see an increase in their strikeouts. 

Name SwStr%  K/9  K-Efficiency
Randy Wells 10.90% 7.09 2.44872
Clay Buchholz 9.60% 6.13 2.29304
Hiroki Kuroda 10.60% 7.13 2.10104
Jaime Garcia 10.80% 7.49 1.87192
Johan Santana 8.60% 5.69 1.81752
Carl Pavano 7.90% 5.14 1.77312
Tim Hudson 6.50% 4 1.732
Scott Kazmir 8.90% 6.07 1.66456
Brett Cecil 9.40% 6.53 1.61624
Luke Hochevar 9.40% 6.58 1.55664

Other notables among the top 30: Ricky Nolasco, Gavin Floyd, Johnny Cueto, Anibal Sanchez, Edwin Jackson.

It’s reassuring to see Nolasco on this list. I mentioned previously that I am very concerned about Nolasco, particularly given his lower K rate. He might not get back to last year, but maybe he should be striking out at least a few more people than he is.

It’s worth noting that Hiroki Kuroda is on this list. One thing I noticed about Kuroda is that while he certainly has the ability to rack up some Ks (a la last night), throughout his career in the United States he has demonstrated a consistent swinging strike percentage as well as a consistent K rate that is around where he is at this season. So it may be that Kuroda simply gets more swinging strikes on non-two strike counts than usual.

And now let’s take a look at those at the bottom of the list. 

Phil Hughes 9.00% 8.53 -1.16776
Justin Verlander 8.20% 8.14 -1.50288
Chris Volstad 5.20% 5.68 -1.57056
C.J. Wilson 6.20% 6.62 -1.69104
Wade Davis 5.80% 6.46 -1.90032
Rodrigo Lopez 4.10% 5.09 -1.96728
Kevin Slowey 5.80% 6.69 -2.17448
Kevin Millwood 6.40% 7.26 -2.25392
Zack Greinke 6.70% 7.78 -2.57376
Yovani Gallardo 8.00% 9.86 -3.75312

It’s disconcerting for me to see Phil Hughes here, I’ve been high on him all season. It’s also unsurprising to see Greinke, despite his lack of wins, we knew he really wasn’t missing too many bats. Yikes.

Other notable names in the bottom 30: Jake Peavy, Brandon Morrow, Max Scherzer, Doug Fister, Tommy Hanson, Jon Lester, James Shields, Chad Billingsley, Clayton Richard.

Also, if anyone sees a flaw in my logic here, let me know. This seems to make sense to me, but I’ll come right out and tell you I’m not a math major.