How the Nationals’ 3 Adjustments Revived Jake Irvin

The Washington Nationals’ pitching staff is making a real leap under new pitching coach Simon Mathews. Jake Irvin stands out as the poster boy for these early gains.

In just four games with Mathews at the helm, Nationals arms are throwing harder, getting sharper movement, and executing pitches with more intent. Let’s dig into what changed, how Irvin shined in his Wrigley Field outing, and what it could mean for the Nationals’ rotation.

Under Simon Mathews: tangible gains in velocity, spin, and movement

Since Mathews took over, Nationals pitchers look more dynamic on the mound. They’re throwing their fastballs and most secondary pitches with more velocity, while also refining the shape and depth of their movement.

There’s clearly a new approach to attacking hitters, with more horizontal movement and sharper inside looks. Jake Irvin’s improvements jump out most, but you can feel the ripple effect across the whole staff.

Irvin’s first 2026 start showed some major changes. His fastball and almost all his secondary pitches came out hotter than in 2025, which finally addresses the lingering worry about his lack of raw heat.

What’s even more interesting is the drop in Irvin’s arm angle—from 32 degrees when he debuted in 2023 down to just 25 degrees in 2026. That tweak led to a dramatic shift in pitch movement.

The slider, especially, looks like a different pitch now. It lost almost 2 mph in velocity but picked up about 9 inches of vertical break, turning into something closer to a sweeper.

This new slider profile vaulted the pitch into elite territory by Stuff+ metrics, hitting a 111 grade and landing among the top 50 sliders in baseball. That’s not something you see every day.

Irvin also reworked his pitch mix to get better matchups. Against righties, he leaned on his sinker (about 30%) and threw more cutters and sliders, while cutting back on the fastball and curve.

Left-handed hitters got a different look. Irvin dropped his heater usage (from 38% to 26%) and curve (from 33% to 23%), mixing in more cutter, changeup, and slider.

The goal? More horizontal, outside-to-inside attacks, with lower sinkers and sharper inside cutters to jam hitters. In his Wrigley Field start, he didn’t give up any extra-base hits—just a couple of solo homers.

Jake Irvin: The standout in a Wrigley Field showcase

At Wrigley Field, Irvin went five innings and gave up two runs. He really looked like the biggest beneficiary of Mathews’ approach.

His fastball had more life. Secondary pitches—especially that revamped slider—looked way more dangerous than last year.

The slider’s new profile, with more vertical break and less velocity, played perfectly off the fastball and kept hitters guessing. A 111 Stuff+ grade on the slider says a lot about how far it’s come and its role in Irvin’s early-season success.

• Velocity gains on the fastball and most secondary pitches—finally addressing last year’s velocity issues.
• Arm angle dropped to 25 degrees, changing movement profiles and helping him use his pitches better.
• Slider turned into a sweeper-like pitch, with about 9 inches more vertical break and a 2 mph drop in velocity, plus that 111 Stuff+ rating.
• Versus righties: more cutters and sliders, fewer fastballs and curves, with more outside movement and inside cutters to jam them.
• Versus lefties: less heater and curve, more cutter, changeup, and slider for better platoon matchups.

All these tweaks point to a clear, deliberate shift for Irvin. He’s blending velocity with movement and getting the most out of his best pitch.

If the velocity sticks and he keeps using his arsenal this way, Irvin could really turn the page and become a steady arm in the Nationals’ rotation in 2026. There’s no guarantee, but the signs are promising.

Slider evolution and the broader impact on the Nationals’ rotation

The slider’s evolution sits right at the heart of this early success story. Irvin’s got a nine-inch increase in vertical break, and the higher Stuff+ grade gives him a weapon that really messes with hitters’ timing—doesn’t matter if they’re righties or lefties.

When he mixes in a faster fastball and a more versatile changeup, that slider turns into the backbone of Irvin’s approach. It lets him go after hitters in spots where he can use his movement and sequencing to his advantage.

Thomas Nestico’s Stuff+ metrics put numbers on the improvement, which helps the Nationals see whether the gains come from real mechanical tweaks or just surface-level changes. The slider’s nine-point jump in efficacy from 2025 to 2026 says a lot about how much pitch design and refinement matter in today’s game.

As Irvin works on his command, especially with that outside-inside plan, it feels possible he could get back to his strong 2024 first-half form—assuming he stays healthy and consistent, of course.

 
Here is the source article for this story: The 3 changes the Washington Nationals made to Jake Irvin to revitalize him