From the moment the Cubs nabbed Josiah Hartshorn in the sixth round of the 2025 Draft out of the Southern California prep ranks and handed him a significant over-slot bonus, they felt like they had something.

It’s why they rewarded the sweet-swinging teenager with four Cactus League games this spring. After impressing there, he quickly proved too advanced for Single-A, becoming the first high school hitter from his Draft class to get bumped up to High-A.

And he’s just kept hitting. Hartshorn, who has flown up the Cubs’ prospect rankings to the No. 1 spot, reached another milestone with his 21st homer of the year, his 16th since joining South Bend in Tuesday's 4-3 loss to Wisconsin at Neuroscience Group Field. The roundtripper gave the 19-year-old 100 RBIs in his debut campaign, as he became the first Cubs teenager to hit that plateau in at least the past two decades.

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As that level of production would indicate, there hasn’t been much of a lull for Hartshorn. He hasn’t gone more than three games without driving in a run since early July. He collected at least 22 RBIs in May, June and July and is sitting at 14 in August with time still to go. But this month has also been near his best in all three major slash categories -- .317/.429/.556. 

“It’s fun to watch, honestly, on a nightly basis,” Cubs president of baseball operations Jed Hoyer said earlier this year. “When you have a prospect really break out and do this, it’s fun for the whole organization. The scouting department feels great. Player development feels good.”

By virtue of reaching triple digits in the RBI column, Hartshorn became just the eighth teenager since at least 2005 to record 100 or more RBIs in a single year before turning 20. He sits fifth overall in the Minors in RBIs in 2026 with less than two weeks to go in the High-A regular season.

Known as a preternaturally advanced hitter in high school, Hartshorn hadn’t been able to swing left-handed for nearly three years. That stroke has returned with a vengeance as he’s mauled right-handed pitching en route to a .934 OPS this year.

"Growing up, I always swung at everything in BP, which helped me understand what I can and can't drive. Or what I can foul off or can't foul off," Hartshorn said in June. "For me, the strike zone isn't necessarily the swing zone. Instead of worrying about ball or strike, it’s more about if I can or can’t drive it."

Hartshorn’s breakout has been rocket fuel for his overall prospect profile. He’s climbed up to No. 39 overall on the Top 100 list, was named to the National League All-Star Futures Game squad and even has a 98 overall card in MLB The Show.

And while Hartshorn stands alone in terms of RBI excellence among recent Cubs teenage prospects, he joins an overall group who went on to make a sizable impact at Wrigley Field. In 2022, Matt Mervis became the most recent Cubs Minor Leaguer to hit the triple-digit plateau (119). Kris Bryant (2014, 110) and Javier Báez (2013, 111) also reached the mark, and both made their Major League debuts the following year.