CSW…WTF?

As the 2021 season has unfolded over the last few weeks, a new pitching statistic has been creeping into game reports and baseball analysis. It is called CSW and stands for “Called Strike plus Whiff Rate”.

Those of us who are easily recognized as “Statheads” have always been trying to gain an edge in evaluating players…especially with regard to our success at Fantasy Baseball. Over the years, we’ve paid close attention to pitching stats such as Earned Run Average (ERA), Walks & Hits Per Innings Pitched (WHIP), Strikeouts Per Nine Innings (K/9), Strikeout To Walk Ratio (K/BB) and a more obscure stat known as “Swinging Strike Rate”, which is calculated by the number of swinging strikes a pitcher gets divided by the total number of pitches thrown. All this is done in an attempt to recognize pitching skills that go beyond what you see on the back of a baseball card.

CSW is the latest arrow in the quiver for those of us with baseball-themed pocket protectors. It adds called strikes to the swinging strike rate to give credit to pitchers for strikes thrown when the batter doesn’t swing. There is some logic to this addition, as a called strike is just as effective as a swinging strike. Now, when you read the summary of a game on your favorite outlet, they just might mention a pitcher’s CSW in evaluating their performance. Just last weekend, Marcus Stroman lasted just four innings and had a terrible CSW rate, while John Gant pitched six shutout innings with an absurdly high CSW. These results were reported on an NBC sports site.

To put this into some perspective, let’s set a guideline. Here are the stats from the 2019 season…

  • Total pitches thrown: 732,473
  • Called Strike Rate: 16.4% 
  • Swinging Strike Rate: 11.2%
  • CSW Rate: 27.7%

With the knowledge that the league average is 27.7%, we can evaluate your team’s pitching staff and see if the hurlers have the right “stuff”.

Looking at the shortened 2020 season, the top ten includes numerous hurlers that you’d anticipate but also a few surprises.

#1 – Jacob deGrom 34.6%

#2 – Dylan Bundy 34.0%

#3 – Shane Bieber 33.8%

#4 – Yu Darvish 33.7%

#5 – Dinelson Lamet 33.4%

#6 – Aaron Nola 32.8%

#7 – Kenta Maeda 32.8%

#8 – Brady Singer 32.3%

#9 – Zack Greinke 32.0%

#10 – Lucas Giolito 31.7%

 The AL Cy Young Award winner (Bieber) and a two-time NL winner (deGrom) aren’t a surprise but did you expect Bundy & Singer? And how about Zac Gallen finishing 11th, just ahead of Gerrit Cole? The rest of the top twenty included the old (Adam Wainwright), the young (Framber Valdez) and a soft-tosser (Kyle Hendricks).

Now, let’s see how our new toy is working after the first four weeks of the 2021 season.

#1 – Corbin Burnes 38.2%

#2 (T) – Shane Bieber 36.5%

#2 (T) – Joe Musgrove 36.5%

#4 (T) – Jacob deGrom 35.5%

#4 (T) – Tyler Glasnow 35.5%

#6 – Trevor Bauer 34.9%

#7 – Gerrit Cole 33.4%

#8 (T) Dylan Bundy 33.3%

#8 (T) Trevor Rogers 33.3%

#10 Huascar Ynoa 32.9%

#11 – Clayton Kershaw 32.8%

#12 – Yu Darvish 32.7%

Even after only a month, it seems like the cream has come to the top. Burnes & Musgrove are reaching their long-awaited potential, Bundy is confirming his status and Kershaw is proving he’s not over-the-hill. What about the two rookies? Rogers is 23, has a 1.29 ERA in five starts and a K/9 rate of 12.2. Ynoa wasn’t even an afterthought in most Fantasy Drafts, yet this 23 year-old has also made five starts with a 2.96 ERA and a K/9 of 11.2.

The remainder of the top 20 shows that Tyler Mahle might be for real (#14 at 32.0%), Adam Wainwright can still fool hitters (#15 at 31.9%) and Nathan Eovaldi’s stuff is still tantalizing (#19 at 31.2%).

Assuming good health, these are the guys to watch. At the end of June, we’ll see how the CSW stat looks half-way through the season. Keep that pocket protector handy.

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