Skenes reduces reliance on his forked sinker and shifts to more traditional pitches.

If one word could summarize Paul Skenes' 2024 rookie season, it would likely be "forked sinker." He has seven different pitch types and continues to use them, but this sinking forkball hybrid is among the deadliest pitches in the game, combining velocity and drop in an unprecedented way.

Skenes started his sophomore season where he left off last year, pitching six strong innings today at Fenway Park as the Pirates defeated the Red Sox 4-2. He improved his win-loss record to .500 for the first time since May 1. He allowed two runs (one earned) and lowered his season ERA to a Major League best 2.05.

Although his record stands at 9-9, such a low ERA—combined with an impressive 10.1 strikeouts per nine innings over 167 innings pitched and a WHIP of 0.95—has made him a strong candidate for the Cy Young Award. Improving on his 2024 performance will be challenging, but there are good reasons to believe Skenes is doing just that.

Interestingly, much of this progress has come without relying on the mixed pitch that took the majors by storm last year. Of the 95 pitches Skenes threw today, only seven were classified as forkballs by Baseball Savant (their current term for the "forked sinker"). Instead, in recent months, he has shifted to another slow pitch: the changeup.

“He’s been using it a lot, and I think he really feels comfortable with it now,” said manager Don Kelly. “He’s able to generate a lot of swings and misses with it.”

Skenes has always had a changeup as a pro, but for most of 2024 it was more of a third option. Today, the changeup ranks as his second most used pitch after the four-seam fastball, and he deployed it in crucial moments. In the fourth inning, with two runners in scoring position, Skenes struck out Nick Sogard with a changeup that resulted in a flyout to center field. Sogard also had chances earlier but grounded out on a changeup. In the fifth inning, Skenes used a changeup to retire Trevor Story, keeping the Pirates’ hopes alive.

Today, the Red Sox sent three left-handed hitters and one switch-hitter against Skenes, creating opportunities for the ace to utilize his slower pitches. On Friday, four of eight swings at his changeup resulted in misses, and none of those four at-bats produced hits.

“I felt like there were several lefties in the box today,” Skenes said. “Traditionally, that’s a pitch you throw to lefties. So when I needed an out and faced a lefty... I don’t know, I just felt like the usage went up. It wasn’t something we planned. It wasn’t by design. We just saw the opportunity and took it.”

It might not have been intentional, but the data backs up this choice. Skenes’ usage of the changeup has increased each month, while his forkball usage has steadily declined.

Pitch usage this season shows a steady decrease in Skenes’ signature “forked sinker” (Source: Baseball Savant).

“When you start throwing one pitch more, some others naturally get used less,” Skenes explained. “Changeups and forkballs achieve good results in different ways. Maybe it’s a philosophy or a game plan, but compared to last year, we’ve just leaned more on it.”

It’s hard to argue with the results. Before Friday’s game, hitters had only a .096 batting average against his changeup, the second lowest in the league behind Jalen Beeks (minimum 200 pitches). It also has the highest swing-and-miss rate (44.9%) among all his pitches, along with the lowest weighted on-base average (wOBA) and expected wOBA (0.103 and 0.133 respectively).

The Pirates needed the changeup to work today, especially since the Red Sox started strong lefty Peyton Tolle, who kept their offense at bay most of the night. The rookie pitcher eventually tired, allowing Tommy Pham and Andrew McCutchen to hit back-to-back doubles in the sixth inning, turning a 2-0 deficit into a 3-2 lead.

After the game, Skenes joked that compared to the opposing pitcher, he was the “experienced veteran,” but the game also served as a reminder that no matter who stands on the mound opposite him, Skenes almost always gives the Pirates a chance to win.

“Fortunately, we have a player like Paul Skenes who commands the ball well and has a proven track record,” McCutchen said. “He did his job, and we managed to score some runs to give him the opportunity to earn this win.”