Well there you have it guys. Top-10 CSW leaderboard through 5 days of the 2021 season. Pack it up and go home - this award season belongs to Trevor Williams so either get on the train or get off the tracks.
In reality let's talk about CSW. It stands for Called Strikes + Whiffs, which is hilarious to realize that the best all these science & math nerds could come up with was Whiff. Where I'm from you usually whiff farts but that's a different blog.
I smell chili
It's a measure of (called strikes + whiffs) divided by total number of pitches thrown. The less pitches, the more strikes that aren't foul-balls, the better off your numbers. It's a simple concept but actually new enough to arouse my interests. Specifically: I like CSW because it represents efficiency on a pitch-by-pitch basis. Comparatively, most stats are at a plate appearance level or aggregated for the season. They're telling you how good someone has been or the likelihood of an outcome. CSW is different to me because you can strip out so much external factors and still get a valid metric. Easy yet practical. That's a double whammy.
Realistically I don't actually think Trevor Williams sustains the near 39% throughout this season. That would be about 10% better than Chris Sale or Gerrit Cole at their best which is kind of preposterous. So I'm going out on a limb here and saying he probably doesn't keep this pace all year but who knows. Baseball's a funny game and I would love to be dead on balls wrong about Trevor Williams's 2021 CSW rate come September. Please dear (baseball) gods make it happen.
In related news I should recognize a weakness: there's not a huge spread between the top and bottom of CSW rates. Like batting average, you actually have to go 3 full decimal points to start separating guys conclusively. On the bright side, it's a great metric to find underrated/undervalued starting pitching. It's not statistically correlated with ERA either meaning you could easily find discrepancies in public perception vs. real value. And now we're talking betting baseball and now my life has come full circle.
For more on CSW:
CSW database 2018-202