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During the recent MLB/MLBPA Rookie Program, MLB Pipeline’s Sam Dykstra caught up with Nationals No. 16 prospect DJ Herz as the left-hander, who turned 23 on Jan. 4, is preparing for his first Spring Training in the Nationals organization.

Herz was acquired from the Cubs in a Trade Deadline deal for third baseman Jeimer Candelario, and he quickly made an impression being named to the Fall Stars Game in November. Shortly thereafter, the Nats added Herz to their 40-man roster and protected him from the Rule 5 Draft.

After reaching Double-A Harrisburg last season, Herz spoke to Dykstra about the steps he is taking toward his Major League aspirations.

MLB Pipeline: It’s been a big offseason for you, specifically with your addition to the 40-man roster with the Nationals in November. What was it like going through that process, and what does it mean to you to now be on the Major League 40-man roster?

Herz: I finished up Fall League, and luckily my mom and my brother flew out. We drove all the way to Arizona in the first place, so I wanted some help to drive back. … As we were driving back, I think the deadline for the 40-man was coming up, and I’m in the backseat while my mom’s taking the turn driving. I got the call from Washington, and he told me I was put on the 40-man. My mom and my brother, we were all celebrating. He told me to take them out to some good breakfast or dinner, whatever time that is. I was like, ‘Of course, man.’

MLB Pipeline: What does a Vulcan grip look like and what makes that changeup work really well for you?

Herz: Basically, when the seams are down like this, so the horseshoe’s down, I spread these two fingers and I try to push it all the way deep down and then I circle change off that. I’m really good at pronating, so I can really get here and then pronate to finish at the end. That’s why I get the downward, little armside run. It’s 10 miles an hour off my fastball. It looks like a fastball all the way to the plate, and then it just drops off. I’m so blessed to have learned that pitch and for [Cubs senior pitching coordinator] Casey Jacobson to put that in my hand because I would have never had that. I was just throwing a traditional four-seam changeup.

MLB Pipeline: What is your approach now to the offseason and going into this Spring Training knowing that you’re technically on the roster, and anybody on the roster is in consideration for a Major League spot?

Herz: One is just kind of homing in on what I’m really good at, the changeup, and being able to consistently throw it in the zone more. Obviously, my thing is walks and being in the zone as much as I can. A lot of that’s coming from staying on-plane, making sure I’m going towards home plate more often and a little less crossfire-y. … Going from the first start of the year to the last start, my mechanics looked so much better and I’m happy with the place it is.

Then, just kind of homing in on the slider and the curveball. I think I was walking 5 percent to lefties this year, and then to righties, it was like 18 percent. So it was a big, skewed line. The slider just gave me a whole other pitch to throw to lefties, and I know I can throw it for a strike, so it became a strike pitch. Now, it’s finding that pitch for the righties and being able to lower that number a little bit.

But it was a big jump from going to 2022 to 2023, and I feel like I’m a completely different pitcher. Now, it’s taking everything that we did in ‘23 and just working a little bit more and getting a little bit better at that type of stuff.