Skip to main content

Using K/BB To Spot 2021 Breakout Pitchers (Fantasy Baseball)

Jan 20, 2021

The sky is the limit for Jesus Luzardo.

In this mini-series, I am doing my best to bring hitting and pitching down to the nuts and bolts, putting aside the nuanced statistics of the recent years, and analyzing in a fundamental fashion. In the hitting post, we stripped it down to just contact rate and hard-hit rate. The goal of every at-bat is to put the ball in play and to do so in a matter that heightens the probability of not making an out while gaining as many bases as you can. On the pitching side, I want to make a case for strikeout to walk ratio being the most important statistic to look at and dive into the numbers a bit.

The only things that pitchers have full control over (meaning their teammates on defense do not play a part) are walks, strikeouts, and home runs allowed. These are the three metrics that most advanced pitching metrics are built off of. FIP, for example, only looks at these three numbers. That metric has proven to be pretty predictive of the future and a much better figure to look at than ERA when looking for future tenses.

So let’s look at strikeouts and walks with a bit of a different approach. Since ERA and WHIP are the two main ratio metrics fantasy leagues use on the pitching side, we will focus on those two spots. While these two categories are not the best indicators of what will happen in the future, they are, of course, great measures of what happened in the past. The goal of pitching is to not allow runs, and ERA directly measures that. The way you give up runs is by giving up hits and walks, and WHIP directly measures that. The goal in fantasy baseball is to predict which pitchers will be best in these categories in the future. We know that looking at a pitcher’s past ERA and WHIP can only tell you so much. We want to find other metrics that better focus on a pitcher’s actual skills while also being predictive of these ERA and WHIP.

Gear up for your draft with our MLB Draft Simulator >>

Strikeout Rate

Using data from 2014-2019 and looking at only pitchers with 50 or more innings thrown, the correlation coefficient between ERA and K% is -.52. The coefficient between WHIP and K% is -.57. These are both significant correlations. You can see these relationships visualized here:

There are outliers, of course, but you can see that in general, as a pitcher’s strikeout rate goes up, his ERA and WHIP go down. It is very rare for a pitcher with a 30%+ to see an ERA over 4 or a WHIP over 1.25.

Walk Rate

The correlations are weaker here, and you can see that a bit in how the dots look less linear above. The correlations are .18 for ERA and .44 for WHIP. That makes walk rate not a significant predictor of ERA (typically, we look for something above 0.3 or below -0.3 before we start calling it a significant predictor). Of course, walk rate has a relationship with WHIP (walks make up half of the numerator in the WHIP calculation, after all), but it is interesting to see that the strikeout rate is a better predictor than walk rate.

Check out all of our 2021 fantasy baseball draft prep content >>

Strikeout to Walk Rate

The coefficient between ERA and K/BB is -0.45, and it comes in at -0.67 for WHIP. That makes strikeout rate the best predictor of ERA, but K/BB the best predictor for WHIP.

Player Analysis

All of those words, numbers, and dots can be summed up in one sentence. It is advantageous to study strikeout rates and strikeout to walk ratios very closely when evaluating pitchers for the future. Looking at the K% leaders from 2020:

This is mostly a list of established fantasy aces. You don’t come to this website to hear people tell you to draft Shane Bieber, Jacob deGrom, and Gerrit Cole. There are a few notable names there, as Tyler Glasnow continued his strikeout heavy ways and the 2020 breakouts of Corbin Burnes, Dinelson Lamet, and Kenta Maeda make an appearance.

Some other notables that made the top 30: Kevin Gausman (32.2%), Carlos Carrasco (29.3%), Zach Eflin (28.6%), Zac Gallen (28.2%), Zach Plesac (27.7%), Framber Valdez (26.4%), Hyun-Jin Ryu (26.2%), and Cristian Javier (25.2%).

Turning our focus to K/BB:

Given that the median value for K/BB is 3.04, the numbers at the top of this list are just ridiculous. The small sample size from 2020 gets the credit for that. Only one pitcher has ever posted a K/BB over eight while throwing more than 120 innings, and that was Clayton Kershaw in 2016 (149 innings, 15.4 K/BB, he had a 31.6% K% and a 2.0.% BB%). Max Scherzer led qualified pitchers in this category in 2019 with a 7.4 K/BB.

For the last six years, a K/BB of 3.7 would put a pitcher in the top 25%. Any value over four can be considered very, very good.

Let’s now look at 2019 and 2020 data together since that sample size is much more reliable than just looking at the goofy 2020 season alone. I filtered out any pitcher that doesn’t have at least 140 innings thrown the last two seasons.

Lots of well-known aces here, but also some sneaky names like Kyle Hendricks, Ryan Yarbrough, Chris Paddack, Michael Pineda, and Tommy Milone. Those names attribute this success more to a lack of walks than a surplus of strikeouts, but they are notable nonetheless.

Breakout Targets

Now we will get to the part you are all likely waiting for. I will offer some names based on K% and K/BB that I think could be incredibly valuable in 2021. I took the 2019+2020 data and examined the K/BB leaders with an eye on 2021 ADP. We really want to find pitchers that are very strong in K/BB but are coming cheap in the draft. Those are potential breakout options, as they are very skilled pitchers but are not being drafted as such for one reason or another. Here’s the list:

Here are some quick thoughts on the pitchers from this list that I am most excited to draft in 2021.

Chris Paddack: Given his limited pitch arsenal (he’s essentially only fastball-changeup, and the fastball is not very good), the upside is capped (for now) with Paddack. However, he continues to display great command, which really raises the floor on him.

Michael Pineda: We just have not seen much of Pineda in recent years (just 172.2 innings in the last three seasons), but he continues to pitch well when he’s on the mound. At an ADP outside of the top 200, I’m all over it.

Stephen Strasburg: The draft price has dropped to a level where all he needs to do is stay healthy to be one of the most valuable players in fantasy this year. Of course, that is a huge “if,” but I think the depressed cost more than justifies the risk.

Carlos Carrasco: He looked just like the Carrasco of old in 2020 and continues to generate tons of strikeouts without giving up many walks. He is a potential top ten starter going in the 6th round or later.

Joe MusgroveBig Joe changed his arsenal a bit last year and raised his strikeout rate above 30%. That was a short sample size, but I believe he’s much better than his career results have shown.

Jesus Luzardo: The 4.12 ERA and 1.27 WHIP were pretty disappointing in 2020, but I think the sky is the limit for this kid. It is pretty rare to find a young pitcher with this strong command, and I think 2021 could be a huge year for the lefty.

That’s all I’ve got, thanks for reading!

Practice fast mock drafts with our fantasy baseball software >>


SubscribeApple Podcasts | Spotify | Google Podcasts | Stitcher | SoundCloud | iHeartRadio

Beyond our fantasy baseball content, be sure to check out our award-winning slate of Fantasy Baseball Tools as you navigate your season. From our Trade Analyzer – which allows you to instantly find out if a trade offer benefits you or your opponent – to our Waiver Wire Assistant – which allows you to quickly see which available players will improve your team, and by how much – we’ve got you covered this fantasy baseball season.

Jon Anderson is a featured writer at FantasyPros. For more from Jon, check out his archive and follow him @JonPgh.

What's your take? Leave a comment

Follow the Pros!

Follow us on Twitter @FantasyPros for exclusive advice and contests