RADIO
If I were on a desert island and had to pick just one statistic to take with me to evaluate starting pitchers for fantasy baseball purposes, I would choose strikeout-to-walk ratio. Would I have bigger problems than picking the best pitchers for my fantasy team if I ever found myself alone on a desert island? Probably. Would I still try to find cell reception so I could play fantasy baseball while I awaited salvation? Absolutely.
In a world with dozens and dozens of metrics measuring baseball pitcher production, it is easy to get lost in the numbers. Every year, we seem to have more statistics to look at as baseball analysts try to make a name for themselves with newer and fancier analyses. While I think that is all fair and good, and sometimes very useful, I do think it can lead to a worse performance by fantasy managers. Sometimes in life, it is better to just keep it simple.
This fantasy baseball writer believes this to be true in evaluating pitchers. I don't really care about how many RPMs a pitcher gets on his slider or the exact heat map of where his pitches ended up last year. I'm a simple man, just tell me how many strikeouts, walks, and ground-balls the induced and I'll be fine.
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What It Is
For our purposes, I am using K-BB%. I'll quickly explain what that is for those of you unaware.
K% - Strikeout Rate. The percent of hitters faced that a pitcher strikes out. If a pitcher faces 100 batters and strikes out 30 of them, that's a 30% K%.
BB% - Walk Rate. The percent of hitters faced that a pitcher walks. If a pitcher faces 100 batters and walks eight of them, that would be an 8% BB%.
K-BB% - This is the difference between K% and BB%. The bigger the number, the better.
So what's a good K-BB%? I could answer that simply, but first I'll show you the whole distribution of K-BB% that pitchers throwing 100+ innings in a given season since 2015 have posted.
The average K-BB% for pitchers reaching 100 innings in a year since 2015 is 14.2%. That basically means the average K% was 23% and the average BB% was 9%, a difference of 14 points. A K-BB% between 17% and 20% could be considered good, between 20% and 25% would be considered great, and above 25% is elite. Anything below 10% is bad, with it getting worse and worse as the number moves towards zero (only one pitcher has actually thrown 100 innings with a negative K-BB%, Tyler Chatwood in 2018).
Only 29 pitchers have gone above 25% over a full season since 2015. The names that have accomplished this: Chris Sale (five times), Max Scherzer (six times), Clayton Kershaw (four times), Gerrit Cole (three times), Justin Verlander (twice), Jacob deGrom (twice), Carlos Rodon, Shane Bieber, James Paxton, Jose Fernandez, Mike Clevinger, Robbie Ray, Corey Kluber, and Corbin Burnes.
Why It's Important
I can answer this question with one simple, and yet beautiful, scatter plot. Here is the relationship between K-BB% and ERA:
What you can see here is a very strong relationship between these two metrics. As your K-BB% goes up, your ERA trends downwards, and vice versa. There are very few examples of a pitcher posting an ERA below four while being under 10% in K-BB%.
When you look at the relationship with other statistics such as exit velocity, fly-ball rate, velocity, spin rate, and those kinds of newer statistics and ERA, you just don't see a very strong relationship. K-BB% is a great predictor of ERA, and there aren't many stats you can say that about.
Biggest 2021 Improvers
I went ahead and looked at every pitcher that threw at least 100 innings in 2021 AND at least 50 innings between 2019 and 2020, and compared their K-BB% figures between those two (meaning I just combined 2019 and 2020 together since 2020 was such a short year). Here is the full list of pitchers that improved their K-BB% in 2021 by at least two points.
We should not only focus on the 'Diff' column here, but also what the actual K-BB% ratio was in 2021. You see that Erick Fedde came in second here, but that is mainly because he was so bad between 2019 and 2020. His 13.6% K-BB% is really nothing to get excited about since that's still below league average. Let's talk briefly about the most interesting names here.
Dylan Cease, Chicago White Sox: Between 2019 and 2020, Cease was just not good. He posted a mediocre 21.5% K% and a horrible 11.9% BB%. He made huge strides in 2021, moving his K% up to 31.9% while lowering his walk rate to 9.6% (this is still not a great number, but you can work with it when you're getting that many strikeouts). He is likely to be one of the biggest ADP gainers in 2022, and for good reason. He is young, was highly touted as a prospect, and his 2021 underlying numbers really back up his strong season.
Logan Webb, San Francisco Giants: It was tougher to see Webb's breakout coming in 2021, but I don't think many people missed it given what he did down the stretch for his team. Prior to 2021, he posted a bad 19.8% K% and an average-at-best 9% walk rate. In 2021 he improved drastically on both numbers, moving the K% up to 26.5% and the BB% down to 6.0%. It is still not an elite strikeout rate, but a very strong combination of the two numbers. His ADP is also certain to explode in 2022 drafts, and it's going to be tough to make a great case against him.
Sandy Alcantara, Miami Marlins: Everybody was seemingly waiting for the big Sandy year, and they got it in 2021. His 24% strikeout rate was still only average, but it was up more than five points from his prior two seasons, which is very encouraging. He has always had great stuff, and he seemed to find additional ways to miss bats in 2021. He did that while lowering his walk rate to 6.0%, which is exactly what he needed to do to take the best step forward. He has been rewarded with a contract extension this offseason, and he should once again be a very reliable arm in 2022.
Robbie Ray, Seattle Mariners: Few pitchers have improved a walk rate in such an incredibly hurry as Ray did in 2022. He went from a 12.9% walk rate in 2019+2020 to a great 6.9% rate in 2021. He did that while increasing strikeouts to 32.1%. It is probably pretty tough to not strike out more hitters when you decide to just all of the sudden lower your walk rate by six points (fewer hitters walking means more opportunities for strikeouts, after all). There is absolutely no reason to doubt Ray's strikeout ability, but it is reasonable to be a little bit skeptical of him repeating a great walk rate with the Mariners in coming years.
Corbin Burnes, Milwaukee Brewers: He led the whole league in K-BB% in 2021 (by a big margin of 1.5 points over Max Scherzer), and his 30.4% mark was good for sixth-best of any pitcher since 2015. It's foolish to think of him as anything but a top-two starting pitcher for fantasy next year.
More Names To Consider
Some other names here that may be cheaper than they should be in drafts:
- Aaron Nola
- Pablo Lopez
- Nathan Eovaldi
- Eduardo Rodriguez
- Clayton Kershaw
- John Means
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