18 whiffs on 24 swings?! 2025 No. 6 pick outduels Yesavage in dominant pro debut

April 3, 2026, could go down as a legendary date in Pirates history.

Not only did the club’s top prospect, Konnor Griffin, make his big league debut and rope an RBI double in his first at-bat, but its No. 2 prospect, Seth Hernandez, officially toed the rubber for the first time as a pro after he was selected in the 2025 Draft with the sixth overall pick -- and he looked every bit the part.

After allowing a first-pitch triple to open his outing, Hernandez settled in and racked up a whopping eight punchouts, surrendering one run over three frames for Single-A Bradenton in its 6-4 win over Dunedin at TD Ballpark. In other words, he recorded all but one of his outs via the strikeout.

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"I knew I was going to be on a pitch count, so I was really just trying to go out there and make sure I'm throwing a lot of strikes to make sure I'm not getting out of the game too early," Hernandez said.

Hernandez succeeded on that front. He landed 30 of his 39 pitches for strikes. Not only that, but MLB’s No. 26 prospect also tallied 18 whiffs on 24 swings, good for a 75 percent whiff rate. That many whiffs at that high of a rate had been reached only one other time since Statcast was installed in Florida State League stadiums in 2021 (former Minnesota prospect Osiris German had 18 whiffs on 23 swings).

If you expand the search to include Triple-A, left-hander Matt Krook had 12 whiffs on 14 swings (85.7%) as a member of Triple-A Scranton/Wilkes-Barre on June 24, 2023. If you include the Major League level (dating back to 2008), Josh Hader had 15 whiffs on 19 swings (78.9%) as a member of the Brewers on May 19, 2018.

Both were dominant outings, but neither as good as Hernandez’s.

Touted out of high school as perhaps the most advanced prep right-hander ever, Hernandez entered 2026 surrounded by hype -- and that was even before the 19-year-old froze fellow Top 100 prospect Max Clark with a 102.4 mph four-seamer at Spring Breakout.

In the California native’s first official start as a pro, his 70-grade fastball was just as electric. Hernandez averaged 97.9 mph and 19 inches of induced vertical break (MLB average is 16 inches) with the offering.

Seven of his eight strikeouts were finished off by either his slider or curveball. One strikeout was secured after a batter pitch timer violation. Hernandez’s pair of offspeed pitches accounted for 12 of the 18 swings-and-misses. The slider in particular -- which registered officially as a cutter because of its high velocity -- produced eight whiffs.

"I kind of figured out early after that first-pitch triple, that they're going to hunt the heater early, so I just learned off of that and started throwing my offspeed stuff a little more early in the count to get ahead," Hernandez said. "And I think it worked out pretty well."

The slider is a tool that Hernandez has been sharpening recently. With the help of the Pirates' pitching development team, he has gained both control and consistency with the offering.

"I was really just trying to throw as hard as I could, and it was getting some good whiffs, especially to the lefties too, because before, I've never really thrown a lot of sliders to the left-handed batters as much," said Hernandez, who throws a four-pitch mix (four-seamer, slider, curveball and changeup).

The Pirates have also helped Hernandez develop his presence on the mound. He has learned to take pride in the little things like holding runners on and using the pitch clock to his advantage.

Mechanically, Hernandez has slightly adjusted his delivery out of the stretch to cut down his time to the plate. Out of the windup, Hernandez's focus is on getting the most out of his back leg. Another wrinkle that comes with being a pro is more in-depth scouting reports, which Hernandez is starting to pick up.

"I think it's now just about actually learning how to read reports and learning what works for me and my arsenal, and learning what also I could actually take into the game and use," Hernandez said.

Taking the mound opposite the 6-foot-4 right-hander was Blue Jays playoff hero Trey Yesavage. The 22-year-old -- ranked as MLB's No. 9 prospect -- fanned three and allowed one run over 2 2/3 frames. The start represented his first rehab outing as he works his way back from a right shoulder impingement.

"I knew that Yesavage was going to throw against me, so that obviously is pretty cool facing a World Series pitcher," Hernandez said. "Glad we got him out of the game early. But other than that, it was a fun first pro outing. My family was in the stands, so it was cool to get the first one over with."

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Hernandez outdueled a big leaguer in his first start as a pro. What could his future outings bring?