Why is Paul Skenes in a Slump?
From poor defense behind him to an increasing launch angle to a change in his approach, Skenes is a different pitcher this year.
There’s something different with Paul Skenes.
In his first nine starts of the season, Skenes had a 1.98 ERA, a 2.51 FIP, and a 10.08 K/9.
In the 13 starts since that point, his ERA is 4.84, his FIP is 2.87, and his strikeout rate is 11.84 K/9.
Skenes has the fifth best FIP and the third best K/9 among qualified MLB pitchers during this stretch. His ERA ranks 59th out of those 69 pitchers.
From a results standpoint, Skenes looks like he’s getting hurt by his defense. He’s striking out more batters during his rough stretch, compared to the first nine starts. His FIP is among the best in the league. And the Pirates legitimately have a bad defense behind him.
Diving in deeper with Statcast data, I wouldn’t put it all on the defense.
Stat: First 9 / Last 13 / 2025 Season
Exit Velocity: 85.7 / 89.5 / 87.6
Launch Angle: 14.1 / 16.8 / 12.2
Barrel%: 4.2% / 7.0% / 5.8%
HardHit%: 29.4% / 43.5% / 40.1%
There are some underlying differences with Skenes that begin to show up in the Statcast data.
He’s getting hit harder. Not as much compared to his 2025 Cy Young results, but still harder. His first nine starts this year were actually better than last season. His last 13 are worse than last season.
The biggest area of concern is a steady increase in his launch angle. Starting in his rookie season, batters are getting the ball off the ground at an increasing rate. He had a 51.3% ground ball rate in 2024, 44.3% in 2025, and 40.8% this year. He’s at 37% during his slump, as the launch angle keeps increasing.
Skenes is working outside of the zone more this year (46.4% vs 50.8% in 2025), but he’s also getting a higher rate of chase swings (33.7% vs 30.4%). He’s giving up more contact, especially out of the zone (61.2% vs 55.7%). What’s interesting is his high contact on chase swings was when he was at his best early in the season. His contact rate on chase swings is at 57.1% during his slump, which is close to last year’s results.
The biggest thing that stands out is that Skenes is attacking hitters over the plate less often this year.
There are some differences with the pitches and delivery.
Despite having better overall strikeout rates than last year, his whiff rate has dropped on almost every pitch he throws.
His arm angle has gone from 23 degrees during his first two seasons to 26 degrees this year.
His sweeper/splitter usage has gone from a combined 38% his rookie season to 30% last year to 26% this year. His offspeed run value has gone from 96-100th percentile the previous two years to 12th percentile this year. Those trends might be related, but the fact that all of his offspeed pitches are seeing fewer whiffs is probably a bigger factor.
So what’s happening with Skenes?
I’m not counting out the defense as a big factor, but it’s not only the defense.
Skenes is pitching in a different way this year.
His arm angle is different.
His attack approach in the zone is different.
He’s getting less swing and miss on every single pitch, but more strikeouts.
His fastball velocity is down about 2 MPH on average.
I stress the word “different” because I don’t want to label any individual change as bad. I don’t know if the arm angle is the root of the problem. I don’t know if the in-zone attack is a conscious effort to work around hitters. I don’t know if that’s related to the fact that he’s getting less swing and miss on every pitch. I don’t know if his arm angle has led to that across-the-board drop in pitch quality, especially offspeed.
The fact is Skenes looks like a different pitcher this year, even if you only look at the numbers.
He’s no longer challenging opposing hitters as often in the zone. Instead, he’s working around them more often. His arm angle is different. Each of his pitches has declined in effectiveness, with a complete 180 in his offspeed value. Opposing hitters are increasingly getting the ball off the ground, where hits become more probable.
Even if you put a better defense behind him, I think Skenes would have a drop in his results this year.
What’s the root of the change? Is it a completely new approach under a new pitching coach? If so, how long will that take before Skenes returns to the pitcher he was, and will that happen at all?
If there was a concentrated effort to change, was it made for long-term health reasons? The arm angle being different suggests a deliberate mechanical adjustment. I don’t think it’s a coincidence this happened at the same time a new pitching coach took over.
Different isn’t necessarily bad.
It’s also clearly not better in this case.
The question is whether Skenes can get back to being one of the best pitchers in the game.
Not just in terms of results independent of his fielders.
He’s still one of the best in the game, which is shown by those FIP and strikeout results.
In a way, he’s almost looking like a smarter pitcher this year, versus previous years.
Then again, he almost has to be smarter, considering his stuff isn’t as good this year.
Imagine if he gets the stuff back to where it was.
Until the next Paul Skenes start…
-Tim Williams