Grading the 2023 KC Royals: John McMillon's abbreviated appearance keeps fans wanting more

The bullpen issues during the 2023 season had the KC Royals taking drastic measures. Promoting a 25-year-old reliever from Double-A is one such measure. But promoting John McMillon to the MLB looked like a great move. For about four games.

John McMillon shot from Low-A to the majors in less than a season for the KC Royals.

McMillon started the season with the Low-A Columbia Fireflies, moving quickly to High-A and then Double-A. He was older than most of his peers at each level, so his moving quickly was not surprising. His getting better after each promotion is what was scary. McMillon had a 0.87 ERA across 20 2/3 innings for the Naturals. He struck out 30 and walked 11 across 15 appearances.

It was more of the same for McMillon, who struck out 91 batters in 51 1/3 innings in the minors this season. McMillon always had the strikeout stuff, thanks to an elite fastball and above-average slider pairing. What made his minor-league performance this season stand out even more was his improved command and control, as he consistently hit his spots and minimized walks. In 2022, he recorded an 11.03.03 BB/9. That dropped to 4.38 BB/9 in 2023. That improvement made McMillon's strikeout ability even more impactful, and the Royals saw that before promoting him.

“He’s got closer stuff,” Royals senior director of pitching Paul Gibson said. “Labeling a closer when a guy is in Double-A is really hard because they have to grow into it. But he’s got closer stuff, closer mentality. Now let’s just see how he evolves.”

In his four appearances, McMillon absolutely looked like he has closer potential. He allowed a home run in his MLB debut, but that is the only blemish on his record. He tallied eight strikeouts to no walks in four innings, with that run being the only hit he allowed. Royals fans should watch how he works closely because McMillon has both the results and stuff to contribute next season.

Unfortunately, a strained right forearm landed him on the 15-day IL 11 days following his debut. He did not pitch again in 2023, robbing fans of more masterful performances.

McMillon is another KC Royals player needing more time to show their fit.

I am bullish on McMillon ahead of the 2024 season. I think he can be a leading arm in the Royals bullpen, and serve as a major win for the team's developmental pipeline. I feel like giving him a grade is unfair, both to him and to others. He receives an incomplete grade from me, but Royals fans should eagerly watch what he does in 2024.