Carson Kelly put a question to his brother: How would Nelson handle his Major League debut?
"He's like, ‘It almost seems like he's done it a million times,’" Carson Kelly said of what his brother told him. "’And he's under control. There's no heartbeat. You have to make sure he's, he's actually out there.’"
Nelson was as cool as the other side of the pillow. If you didn't know going in that he was making his debut, you would not have known it by how he carried himself on the mound. He was poised and in control in throwing seven shutout innings in a 5-0 win over the Padres at Petco Park.
"A real good curveball 12-6, good slider, good changeup that got some really bad swings," Padres manager Bob Melvin said. "You’re hoping after the first time through the lineup, you get a little better sense of what he’s doing. But he got stronger as the game went along."
Indeed, the best chance the Padres had against him came in the first when Jurickson Profar led off the inning with a double to right-center field. Though Profar advanced to third, Nelson retired Juan Soto, Manny Machado and Josh Bell -- the heart of the Padres’ order -- to strand Profar.
"If we would’ve done something there, I think that would’ve changed the whole outcome of the game," Machado said of the first. "But he got under control and he started making good pitches and keeping us off balance a little bit. He had his stuff. It was a good Major League debut."
Nelson was picked by the D-backs in the second round of the 2019 MLB Draft and spent this season with Triple-A Reno, where the 24-year-old made 26 starts and had a 5.43 ERA.
An ERA in the Pacific Coast League can be deceiving, though, and the D-backs’ decision-makers elected to give him this opportunity because they felt like he had good enough stuff, was landing pitches in Triple-A and that he would be able to handle it.
Nelson, ranked by MLB Pipeline as the D-backs' No. 8 prospect, felt nerves Sunday night when the team arrived in San Diego and again Monday morning. But they didn't last.
"Just the build-up and stuff like that,” Nelson said. “But once we got out there and threw the first strike, it all went away and I just played the game I've been playing forever."
Where some pitchers can allow the nerves of their debut to cause them to nibble at the strike zone, Nelson went right after the Padres. Only once all day did he go to a three-ball count and that was to Bell in the seventh inning.
"To give myself the best shot, I have to be aggressive and throw the ball over the plate," Nelson said. "If I start falling behind it's going to spiral real quick. So I just tried to get ahead, throw all my pitches for strikes and let the game happen."
Nelson's fastball is good, reaching a maximum of 98.1 mph on Monday, per Statcast, and averaging 95.1 mph, but what makes it better is that it has good life on it, which makes it harder for hitters to square up.
"We just couldn’t hit him," Machado said. "His fastball -- he threw his fastball for strikes. A little tough to see."
Nelson’s debut line -- seven innings, no runs, no walks and seven strikeouts -- was nearly unprecedented. In AL/NL history only one pitcher broke in by throwing at least seven innings and recording seven strikeouts while posting zeros for runs and walks. That was Pittsburgh’s Nick Kingham against St. Louis in 2018.
Nelson watched Soto and Machado on TV when he was younger. They are two of the biggest stars in baseball. What did he think when he faced them for the first time?
"It kind of just makes you realize where you are and makes you feel good," Nelson said. "You've worked really hard to be able to face guys like that.”