Early Pitching Outliers: Swinging-Strike Rate vs. Strikeout Rate

April 29, 2022

Jon analyzes the relationship between swinging-strike and strikeout rates to determine which starting pitchers could be fantasy baseball risers or fallers.

It is very early in the season, as the league leaders have made just four starts. Because of this, we have a lot of strangeness in the data that has been generated, especially with pitching, which is an inherently random exercise.

One thing that can be a bit random over a small sample size is the strikeout rate. This does turn out to be one of the quicker statistics to stabilize, but early on, a few extra strikeouts here and there make a substantial difference on your strikeout rate, giving umpire calls and other outside influences a bigger grip on the final rates.

One statistic that tells us a lot about what to expect for a strikeout rate would be the swinging-strike rate. You have heard a bunch about this statistic, to be sure, but to review: Swinging-strike rate (SwStr%) is the percent of a pitcher's pitches that generate a swing-and-miss. Most of baseball's strikeouts come from swings and misses, here is the breakdown of that so far in 2022:

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Early Strikeout Data

Since most strikeouts are of the swinging variety, we know that the swinging-strike rate should be highly correlated with the strikeout. This turns out to be true, and it gives us the opportunity to look at pitchers whose SwStr% and K% metrics don't really match up.

The Relationship, Plotted

Here is every qualified pitcher and their SwStr% and K% plotted. I've added a trend line to show you that relationship, as your SwStr% goes up, so does your K%.

You can hover over or click on each dot to see who it represents. The pitchers that are very close to the line are basically "nothing to see here" guys, meaning there's nothing outlierish about their SwStr% and K% combination. The dots that are far away from the line is a different story and we should probably expect them to come back towards the line, meaning their strikeout rate is likely to come up or down as we move forward.

Positive Outliers - More Strikeouts To Come

Kevin Gausman, Toronto Blue Jays

data does not reflect Tuesday's games

This is more about just how absurd the swinging-strike rate has been so far. For comparison's sake, Corbin Burnes led the league in SwStr% last year with a mark of 16.6%. You can see Gausman's 22.7% is well above that, and certainly not to be sustained.

What we can say is that he probably should have earned a few more strikeouts in those first starts, and if he keeps this SwStr% above 15%, I would expect a few extra points on the K% eventually. There's nothing really actionable with Gausman, he's an ace and you may have gotten a nice deal on him on draft day - hold on tight.

Kyle Gibson, Philadelphia Phillies

It's been a pretty encouraging start to the year for Gibson. He has generated 17, 17, 10, and 17 swinging-strikes in his four starts (ordered chronologically), which is something we're not used to seeing from him. Last season, the SwStr% on Gibson was just 10.3% and that came with a predictably low 20.6% K%. Those numbers make sense. Now, his SwStr% is up to 17.1% through four starts, and the K% has followed, but probably not quite enough.

The thing with Gibson is that it's foolish to believe he can really be a guy with an SwStr% above 12% or so. However, it's not crazy to think he could hold on to some improvement from last year here, which would make him a much more interesting fantasy pitcher. He does everything else pretty well (52% GB%, 8% BB% last season), so a few added strikeouts could really turn him into someone you want to start on your fantasy teams.

The thing benefitting Gibson right now may be the schedule he's faced. He's taken on the Athletics, Marlins, and Rockies twice - three offenses that are not good. I'd probably expect Gibson to end up back around 10% SwStr% and 21% K%, but he's worth monitoring for now.

Alek Manoah, Toronto Blue Jays

Manoah was awesome in his rookie year at generating swinging-strikes (12.8%), and that's continued this year. What hasn't followed is the strikeout rate, which sits right around the league average at 25%. The command has been a bit of an issue, as he's walked six batters through three starts, so that might explain a bit of this. Since he didn't have an overly high walk rate last year (8.7%), I'm not going to fret too much over that. Manoah's stuff is legit, and he should continue to get better and better as he gets more experience. He's someone to be excited about.

Tony Gonsolin, Los Angeles Dodgers

Gonsolin recently generated 13 whiffs against the Braves but was rewarded with just three strikeouts for his efforts. That start has a big disparity here. I absolutely expect Gonsolin to bring that K% well above 15%. He finished at 20% last year, so that's not a high number - but it's certainly much better than 15%. The one thing Gonsolin has going for him this year that he hasn't in the past is a bit of job security. The Dodgers do not have a deep rotation right now with Andrew Heaney on the shelf, which is uncharted territory in recent years. Tony G should stick in the rotation, and I expect more strikeouts to come - but don't get your hopes up too high, the ceiling is pretty low.

Other positive outliers: Gerrit Cole, Garrett Whitlock, Joe Ryan, Keegan Akin, Frankie Montas

Negative Outliers - Fewer Strikeouts To Come

Nestor Cortes, New York Yankees

It was almost a sure thing that the league leader in K% after three weeks of games was going to be overperforming. Nobody in their right mind expects Cortes (or any pitcher for that matter) to sustain a strikeout rate above 40%. But just to make the point, his swinging-strike rate isn't even really in the "elite" realm despite the crazy high strikeout totals.

The start where he did most of his damage came with 12 strikeouts but just 15 whiffs. That's a really surprising ratio to see. The league-wide ratio of swinging-strikes to strikeouts is 2.11, meaning we see one strikeout for every 2.11 whiffs. Cortes' ratio right now is 1.36. We know the strikeout rate is coming down, I'm not saying anything interesting by typing that. I imagine this guy's strikeout rate settles down around 26-28% when all is said and done. To me, that makes him a guy I'd be shopping around to see if I can get somebody to bite on the elite start to the year.

Adam Wainwright, St. Louis Cardinals

The ageless wonder has 22 strikeouts this year, and 10 of those have been looking. That's 45% of his strikeouts, much higher than the league's 24% rate.

We would expect to see Wainwright on this list, as a guy who makes his living with pinpoint location and called strikes, but this ratio is just ridiculous. If you scroll back up to look at the scatter plot, his dot is by far the biggest outlier on the map.

Right now, there are 42 qualified pitchers with swinging-strike rates under 10%. Of those pitchers, only eight of them have strikeout rates above 20%, and Wainwright leads the back with a mark of 24.2%. The average strikeout rate of this group is 16%. Last season, Wainwright went for an 8% SwStr% and a 21% K%. I would say that's about where we should expect him to be this year as well, but I wouldn't be surprised if he falls short of both of those numbers given how old he is getting.

Eric Lauer, Milwaukee Brewers

His numbers here are buoyed by a huge performance last Sunday where he struck out 13 Phillies. That outing was completely uncharacteristic for him. Last season, his K% finished at 24% and he has only struck out 10 batters in his other two starts this year.

His 13.1% SwStr% is strong, but it's far from the elite tier here while his strikeout rate sits just outside of the top-10. I'm not buying Lauer as anything more than a 27% guy this year, and I'd be shopping him after that big outing on Sunday.

Alex Wood, San Francisco Giants

Wood is just a solid pitcher, and he's fitting in great with the Giants. His strikeout rate is right on par with what he did in 2021, but his SwStr% is actually down two points. I think we can count on a 24%+ K% from Wood, which is more than good enough given the quality of contact he allows and the nice walk rate, but if he doesn't start generating some more whiffs, we could see this K% tick downwards soon. I would be holding or acquiring Wood if the price is right though, nothing really to worry about here.

Taylor Hearn, Texas Rangers

Hearn isn't rostered in many leagues, but he has looked improved early on with a nice 24% K%, way up from his 21% mark last year. The trouble is the whiffs just aren't there, as he sits right there with Wainwright in terms of a high K% with a low SwStr%. I'm not buying what Hearn is selling.

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