In-Season Pitching Improvers

Looking at the pitch modeling data to see which pitchers have made the biggest improvements during the 2024 season.

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I finally have an afternoon with some free time to run another free bonus piece. This time, we’re looking at starting pitchers to determine which guys have had the biggest increases and decreases in the Pitching+ data model.

The data I’m using is from FanGraphs now, and I import it daily through their API so I can do this kind of analysis. If you’re a big baseball stats guy and you have a few extra bucks free monthly, I recommend supporting them by becoming a paid member. I’ve been one for a long time now, mostly just out of gratitude to them and how much time I’ve spent on their website, but it’s also a much more pleasurable experience not having to deal with the ads on their site.

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I did not pick an arbitrary date to compare with here. For each pitcher, I looked at their number of starts, divided that by two, and split it in that fashion.

I’ll show you my data source here because I know there are a lot of aspiring data bro’s out there who appreciate that kind of stuff. Here’s what the Corbin Burnes rows look like:

Having the data in this format gives you a whole lot of potential to do stuff like this:

In Burnes's example, we see that he made 16 starts, and then we compare his first eight with his second eight. Now that you understand what I’m doing here, I can go ahead and get to the results.

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Pitching+ Gainers

This is probably the most important of the three pitch modeling metrics because it is most closely correlated to on-field results. Pitching+ takes into account the pitch's movement and locations to grade each pitch based on its likelihood of getting a certain kind of result.

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Ryan Weathers

First Half Pitching+: 94.0
Second Half Pitching+: 100.8

First Half Stuff+: 99.2
Second Half Stuff+: 88.3

First Half Location+: 92.8
Second Half Location+: 98.6

This isn’t a great name to start with since Weathers is currently on the shelf. He could return in the next few weeks, but you probably don’t want to add him now. But know that he was looking quite good in three of his recent starts as he had piled up 26 strikeouts in 19 innings between May 20th and June 1st. If he gets back on the hill soon, he is worth a look in deeper leagues.

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Gavin Stone

First Half Pitching+: 96.3
Second Half Pitching+: 102.5

First Half Stuff+: 94.4
Second Half Stuff+: 97.6

First Half Location+: 100.1
Second Half Location+: 103.7

Remember that this data takes two days to get to me, so the numbers from his complete game shutout last night aren’t included.

It’s not surprising to see Stone here, and it’s really encouraging as well because he’s been awesome lately after a slow start. Over his last eight starts, he has given up just 12 earned runs in 51 innings with a 21.4% K% and a 6.0% BB%. Given that he’s a member of the Los Angeles Dodgers, he has been piling up the wins, winning six games in these last eight starts and having nine on the season, second-best in the league (Sale, Suarez, and Lugo have ten).

Often, these pitch modeling changes will have something to do with a change in the pitch mix. If you throw a high Stuff+ pitch more often, your overall Stuff+ will increase. I don’t think that’s the case with Stone. The mix has stayed pretty steady. There have been a few starts lately with heightened slider and sinker usage, but it’s not a striking difference.

It seems that Stone is just a young pitcher figuring out big-league hitters and benefiting from the fantastic development staff the Dodgers have. The 25-year-old righty's future is looking bright.

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Tyler Glasnow

First Half Pitching+: 104.4
Second Half Pitching+: 110.5

First Half Stuff+: 116.4
Second Half Stuff+: 115.8

First Half Location+: 101.8
Second Half Location+: 103.9

If any pitcher didn’t need to improve in the middle point of his season, it was Glasnow. He has been awesome all year and is the Cy Young favorite right now. But he has gone ahead and added six points to his Pitching+ since mid-May. Silliness.

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Carlos Rodon

First Half Pitching+: 100.0
Second Half Pitching+: 105.9

First Half Stuff+: 116.6
Second Half Stuff+: 123.8

First Half Location+: 96.9
Second Half Location+: 98.0

Rodon looked extremely average in the early going, but over his last eight starts, he has raised his Pitching+ to a very strong mark of 106.

This one does look like it has a lot to do with pitch mix:

Pitch: First Half %→ Second Half %
FF: 56% → 49%
SL: 24% → 27%
CH: 6% → 13%
FC: 11% → 2%
CU: 3% → 9%

Reduced fastball usage (16 points between the four-seamer and cutter) in favor of his secondaries with the slider (+3) and changeup (+7). That is certainly a formula for more strikeouts and better results if you can command the pitches, and he has done that well enough with a 98 Location+ these last eight starts. Good stuff from the crafty veteran.

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Logan Gilbert

the plot shouldn’t start where it did, but I didn’t want to spend time messing around with the code

First Half Pitching+: 100.3
Second Half Pitching+: 105.8

First Half Stuff+: 120.3
Second Half Stuff+: 115.0

First Half Location+: 99.5
Second Half Location+: 104.0

Gilbert has been one of the quieter aces in the league for a while now. He goes out there and puts up great numbers and does not get talked about a lot, as far as I hear, at least (but I’m a long way from the West Coast and go to bed at 10:30…). These increases are hardly notable because he’s just been great all year long:

First 8 starts: 2.94 ERA, 0.94 WHIP, 27.1% K%, 7.5% BB%
Last 8 starts: 2.48 ERA, 0.85 WHIP, 22.2% K%, 3.0% BB%

He has gone back and forth in his career between getting a lot of strikeouts and not. In other situations, I might get worried about a five-point reduction in strikeouts, but it's fine when you’re still putting up a sub-one WHIP with a corresponding large drop in walks. Gilbert is an ace.

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Reynaldo Lopez

First Half Pitching+: 98.2
Second Half Pitching+: 103.3

First Half Stuff+: 95.7
Second Half Stuff+: 93.9

First Half Location+: 100.5
Second Half Location+: 104.3

I would have guessed he’d be on the other side of this. He threw 66 innings last year in a bullpen role and now has thrown 79 innings in three months in a traditional starter’s role, and it’s gone amazingly well. He sports a 1.70 ERA with a 17.1% K-BB%. There will certainly be ERA regression, but so far, he’s held up. His second-half ERA and K-BB% are both significantly better than his first-half marks.

The Pitching+ improvement is coming more from command than stuff. You can see he’s lost a few points in Stuff+.

I am still looking to sell Lopez, given the questions about whether anybody can really go from 60 innings to 160 innings without fatigue setting in, but he is making it tougher to want to lose him.

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More Names

Here is the full list of pitchers with at least a three-point boost in Pitching+ in their second half.

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Pitching+ Decliners

Graham Ashcraft

First Half Pitching+: 100.5
Second Half Pitching+: 91.5

First Half Stuff+: 111.3
Second Half Stuff+: 113.2

First Half Location+: 104.1
Second Half Location+: 93.6

We have never cared much for Ashcraft in the fantasy game, so this will be quick. He has long been a guy who stands out in Stuff+ models while not putting out anything good in the real-life results. That is because he throws a very hard cutter. It’s a pitch with few comparables because most guys don’t throw their cutters anywhere near that hard. That makes the pitch modeling stuff have trouble because there is less data to train on.

Highest Average Velo on Cutters - 2024 (250 pitches minimum)

What Ashcraft was doing in the first half was commanding his stuff well. That has not been the case for him in the past, and it didn’t last. He now has a 5.45 ERA and a 9.8% K-BB% and can be happily left on the waiver wire.

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Jared Jones

First Half Pitching+: 114.6
Second Half Pitching+: 106.0

First Half Stuff+: 136.1
Second Half Stuff+: 118.3

First Half Location+: 105.7
Second Half Location+: 101.0

The beginning of the season for Jones was simply too good to be true. He was throwing with elite velocity, elite movement, and near-perfect command.

Everything has regressed in his most recent outings, but he’s still been a very good pitcher with a 106 Pitching+, 118 Stuff+, and 101 Location+ in these last eight starts. There’s been some bad luck in there, and it’s given him a poor 4.85 ERA and 1.38 WHIP in the second half, but I’m confident he’ll settle somewhere comfortably in between these two halves. He’s not a fantasy ace, perhaps, but he remains a strong option.

We will begin to see workload management. It appears that his next start is being skipped or at least pushed back a few days, and that makes sense, given his age and the Pirates’ long-term plans for this young rotation of theirs.

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Luis Castillo

There was missing data from his April 20th start, so that start is excluded here

First Half Pitching+: 107.5
Second Half Pitching+: 99.0

First Half Stuff+: 98.4
Second Half Stuff+: 99.8

First Half Location+: 109.0
Second Half Location+: 101.2

Castillo is firmly within the circle of trust now, so it’s wise to ignore the in-season variance. He does have a discouraging 4.37 ERA and just a 19% K% in his last eight starts, though. And when you see the Pitching+ mark has fallen below average over the same timeframe, maybe there’s reason for concern.

Unless we hear something about a possible injury, I’d be buying on the proven righty.

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Justin Steele

First Half Pitching+: 107.0
Second Half Pitching+: 99.0

First Half Stuff+: 99.8
Second Half Stuff+: 102.8

First Half Location+: 104.9
Second Half Location+: 100.6

Steele has done his best work lately, and he is such a unique pitcher that modeling doesn’t fit him very well. I’ve even heard some stuff about him constantly mixing up how his fastball flies during AB’s just to keep hitters off balance. That’s how Steele has made his career: keeping hitters off balance. So we’re not going to worry about his marks here.

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Shota Imanaga

First Half Pitching+: 106.1
Second Half Pitching+: 99.7

First Half Stuff+: 97.8
Second Half Stuff+: 82.6

First Half Location+: 104.8
Second Half Location+: 102.9

Another “too good to be true” start here. He has had two bad starts all year, but they have both been in his last five starts and have been really bad. He’s given up 17 runs in those two starts and just nine in his other 12 starts.

The red line there is striking. He has posted Stuff+ below 100 in each of his last six starts and has been under 100 Pitching+ in four of his last eight starts after flying above 100 in each of his first six.

I’m unsure what to think about Imanaga, but I’d be lying if I said I wasn’t worried about him. And it’s hard to sell a guy after he gives up 10 earned runs in a single start! We’ll see how it goes today.

More Names

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That will do it for this free analysis post. The full data is available to paid subscribers below the paywall. That is all that’s behind it, so you aren’t missing out on more analysis in this case if you aren’t a member. Thanks for checking it out!