Early-Season Outliers - Players to Buy or Sell for Fantasy Baseball

May 5, 2023

Jon's fantasy baseball buy/sell trade candidates for Week 6. He analyzes early-season outlier statistics that should be expected to regress toward the mean.

I wrote this post a handful of times last year, and I wanted to get back to it. It is probably best to run about once a month, so let's get it started here.

A lot of weird stuff can happen in the game of baseball over a small sample. One month of games, which is about what we have at our fingertips right now, is something I would consider a small sample size. But the thing about it is that it's not so small that everybody would view it this way. You're not going to be able to buy low on a struggling pitcher after two starts, right? The manager who has that player won't be worried yet. But after six starts, you just might be able to do it. That's where we're at in the season right now, we have too little data to actually believe in a lot of cases, but enough data to where a lot of people will be believing it.

So I want to comb through some data points today to find the biggest outlier statistics that have been generated so far. These will go in both ways, good and bad - and it should give us some ideas of what players are good buy-low and sell-high options.

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Outlier #1 Bad Luck Slugging

Josh Naylor, Ryan Mountcastle, George Springer, Kyle Tucker

There are plenty of hitters underperforming their expected slugging percentages. There is one simple way to find these names, and that's just by looking at the SLG - xSLG leaders on Baseball Savant.

I took another step and checked xwOBA against actual slugging:

I did not highlight Springer there because he wasn't a part of the original plan here, but he really does stick out with the xSLG so he should be considered quite unlikely as well.

Naylor: He's not jumping off the page with his contact (8.9% Brl%, 79% Contact%), but he's been very solid in that regard and he's hitting the ball hard quite often (46%). What has made him pop up here is just how crazy low his slugging percentage is. He is still making a ton of contact and hitting the ball well, they just haven't been falling in. He's a very good buy-low target.

Mountcastle: The park plays a big part here. The slugging percentage by right-hand hitters on line drives and fly balls over the last two seasons (since the park changes) has been just .762. Compare that with the league average slugging percentage on line drives and fly balls of .837 and you can definitely tell that deep left field fence has been murder on right-handed power. That fence isn't moving, but what Mountcastle has done with the bat this year is just incredible. He has the second-most barrels in the league with 18, he's kept the strikeout rate under 20%, and his xwOBA is one of the tops in the league above .400. Maybe he'll never be able to be the 35+ homer guy he could be in another park, but better results should be coming for Mounty nonetheless.

Tucker: He's just doing what he always does, consistently making great contact, not swinging at bat pitches, and not striking out much. But the results haven't come as expected, but it's coming.

Springer: The Blue Jays have been a joyous offense to be a part of, but Springer isn't getting a big piece of that pie with just a .292 SLG this year. The good news is the 18% K% and 10.3% Brl% - numbers that suggest a much, much higher SLG than what Springer has. Hang in there.

Sandy Alcantara's Strikeout Rate

We can predict a pitcher's strikeout rate pretty accurately just by seeing the SwStr%. Here's some more detail on that:

You can use that mapping table to see which pitchers are under or over-performing in strikeout rate. Right now, Alcantara has a 15% SwStr%. By the table above, that should be turning into something like a 26-28% K%, but in his case right now he sits with just a 21% strikeout rate.

It hasn't been a good year for Alcantara to this point, but raising his strikeout rate by a handful of points would certainly help those results improve - and it looks likely that we'll see that K% start to tick up in the future starts.

Here's a scatter plot to make that point even clearer. You can see the relationship between the dots going up and to the right. Alcantara's dot stands out quite far away from the cluster of dots in the middle, and you can see where the other names are that are between 14% and 16% SwStr%.

Other names under-performing based on this kind of approach:

As for some pitchers that might be over-performing, we can look at the highest K% pitchers with SwStr% below 12% (the league average):

• Mitch Keller (11.2% SwStr%, 27.9% K%)
• Kodai Senga (11.7% SwStr%, 27.4% K%)
• Logan Webb (11.1% SwStr%, 27.0% K%)
• Hunter Brown (11.9% SwStr%, 25.7% K%)
• Clarke Schmidt (12.0% SwStr%, 25.7% K%)
• Drew Rasmussen (11.4% SwStr%, 25.6% K%)

Nick Lodolo's ERA

Great American Ballpark is not a good place to pitch. It can bloat ERAs in a hurry with the cheap homers that happen there. However, Lodolo has been extremely unlucky this year even considering the home park.

Among pitchers with at least five starts made, only 27 have K-BB% over 20%. Nick Lodolo is one of them at 24.1%. The average ERA of that bunch of pitchers is 3.08. But Lodolo's ERA is way up there at 6.16 - the highest of the bunch (the 29th-highest ERA out of 140 qualified pitchers).

Strikeouts have not been an issue for him early on (31%), and the walks have been great as well (5%). There are certainly going to be better times and a much, much lower ERA ahead for him if he keeps this K-BB% anywhere near where it currently is. The talented young lefty is a superb buy-low candidate right now.

Other pitchers that fit this mold (but to a lesser extent): Chris Sale, Lance Lynn, Brady Singer, Jose Berrios, JP Sears, Clarke Schmidt

Matt Chapman's Lack of Homers

Chapman has been driving the ball better than anybody in the league since the first pitch of the season was thrown. He is way ahead of the field in barrels, but that hasn't translated into homers for him.

Barrels Leaders as of May 4th

That's a 20% HR/Brl rate, which is miles away from the league average which is around 48%. No other hitter with double-digit barrels comes close to that mark. And it's not like Chapman is playing in a pitcher's ballpark either, at the very least Rogers Centre is neutral.

It's no guarantee that the barrels will keep coming in bunches like this (in fact his 30% Brl% right now is certainly unsustainable), but it's also a very good bet that his HR/Brl rate will end up above 40% - and that means more homers are likely coming from the Blue Jays third basemen. Hold on tight to him.

That's it for this edition of MLB Stat Outliers, thanks for reading - let me know what you think on Twitter!

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