Improving Pitchers to Go Get Now!

May 19, 2021

Jon Anderson analyzes starting pitchers to target in fantasy baseball through trades based on early-season improvements in 2021.

When it comes to starting pitching, data generated in the month of May is more useful than data generated in April. This is my opinion. The reason for that is because so much of pitching is about arm health and pitcher routine. I have never played baseball at any serious level, but I can imagine that pitching for the first few weeks of the season is a different story than the rest of the season after these guys settle in a bit.

We often see limited pitch counts in the first few starts of the year as pitchers build up their arm strength and teams play it safe, not wanting to subject their prized pitchers to unnecessary risk. After a handful of starts, pitch counts level out and it becomes safe to say that the league's pitchers are going 100%.

For this study, I took every pitcher in the league and divided their 2021 seasons right down the middle. If a guy has made six starts so far, I compared his first three to his last three. The goal here was to find some players that have been much better in their last few starts than they were in their first few starts. This improved performance could, of course, just be due to randomness, but it's also quite possible that their early-season struggles were just due to them not being fully built up and in their routine yet. So here we go, here are some names to think about acquiring due to improved recent performance.

Zach Plesac, Cleveland Indians

Plesac tops the list in terms of pitchers with increased velocity on their four-seam fastball. From April 3rd to April 20th, Plesac's fastball averaged 92.2 miles per hour. In his last three starts from April 26th to May 13th, it has averaged 94 miles per hour. Here's the start-by-start plot:

That increased velocity hasn't turned into huge improvements in SwStr% or CSW%:

But there are slight improvements there and the consistency is back. His last four starts (not including the start on May 18th because this post was written before that outing) have been brilliant, giving up four earned runs in 27.2 innings. The strikeouts haven't been there this year with just 33 over 48 innings, but everything else has been looking great for Plesac.

The recent surge may have gone on for too long to make Plesac a cheaply attainable player, but maybe someone in your league is sick of the low strikeout totals and would still sell a little low on the righty.

Jack Flaherty, St. Louis Cardinals

Flaherty has taken advantage of some soft match-ups against the Brewers, Marlins, Reds, and Rockies recently. Over those four starts he has given up just a single run in 26 innings while striking out 24. The success cannot be just chalked up to the matchups though, look at his fastball velocity improvement:

The CSW% and SwStr% have also been trending upwards:

The strikeouts are still more average than elite, but man Flaherty has been very, very good in every other element of the game so far this year. He is a very strong SP2 if not an SP1 moving forward. I would be more than willing to give up an ace with a little more injury risk (say a Max Scherzer) for Flaherty if I could get something extra along with it, like a strong hitter or a great reliever.

Garrett Richards, Boston Red Sox

Richards was once a very interesting arm for fantasy purposes. He was always one of those guys that would be very good while he was on the mound, but just could not stay healthy.

It seems he is back to being that guy again right now. After a few starts of being just horrible, he has turned it on in a hurry:

You can see the velocity has been coming up and the CSW% and SwStr% rates have also been improved since those first few rough outings.

Recently he has thrown three strong starts against the Rangers (5 IP, 1 ER, 7 K), Athletics (6 IP, 0 ER, 4 K), and Mets (7 IP, 1 ER, 10 K), so he has been brilliant for any fantasy team that was on top of this. He is widely available (just 18% rostered on Yahoo and 20% on ESPN), and there's a good chance he is a better bet for the short-term than the worst pitcher on your roster currently.

Yusei Kikuchi, Seattle Mariners

Much has been written about Kikuchi on this website, and for good reason. He has been quite good since going through a brutal schedule stretch where he faced the Twins, Astros, and Red Sox. Since then he has made four starts (against the Astros, Orioles, Dodgers, and Tigers) and has thrown 26.1 innings to the tune of a 3.08 ERA, a 0.88 WHIP while striking out 33. Here's the SwStr% and CSW% progression:

Typically what you're looking for in the CSW% category is 30% or above. Anything significantly into the 30s is very good. Kikuchi has been over 30% in five of his eight starts, and above 31% in his last four. He's been great.

Possibly the best part about Kikuchi is the high ground-ball rate he gets, which should help him limit the damage even if the strikeouts do tick downwards a bit. I would consider Kikuchi nearly a must-own pitcher moving forward, and he can still be acquired on the waiver wire in a lot of leagues.

The Rest of the Data

I decided to just go ahead and publish my data source for you all to enjoy. It is searchable and sortable. I did filter it down quite a bit. It's restricted to only pitchers that have thrown 400 or more pitches this year.

You see only the "differential" columns below, which means I'm not showing you the actual numbers for the first and second halves, just the difference between them. A positive number means their second-half number has been higher than their first half, which would be a positive sign for the pitcher. Enjoy!

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