It looks like Frank Mozzicato has added a slider

The Kansas City Royals took Frank Mozzicato with the seventh overall pick in the 2021 MLB Draft. For many, it was surprising but he’s done well thus far in the minor leagues. He hasn’t been elite, by any definition of the word, but he’s still just 20 years old and progressing very nicely. He started his professional career last season for Low-A Columbia and pitched to a 4.30 ERA over 19 starts. His strikeout totals were impressive, with 89 over just 69 innings. However, the walks were way too high and his command was spotty.

This year, he started his season once again in Columbia but looked much better. Over 12 starts there in 2023, he owned a 3.36 ERA with a 13.6 SO/9. His walks were better, but still too high at more than five walks per nine innings. Still, the progress he showed earlier this season was enough for the Royals' pitching development team to feel comfortable promoting him to High-A Quad Cities in early July.

Since heading to Davenport, the results have been far from pretty. Over seven starts for the River Bandits, his ERA is all the way up to 8.13. His walk rate at the level would be the highest of his pro career thus far and the strikeouts are still good, but down. On Tuesday, the reasons for his tough adjustment thus far may have become a little more clear. Mozzicato — who has historically thrown a curveball, changeup, and fastball — looked to mix in a slider at times.

According to Matt Hinkley, Pitching Coordinator for Cressey Sports Performance, Mozzicato developed a slider this past off-season and it was pretty darn good.

To this point, however, the slider wasn’t something that showed its face in game action. That is, until Tuesday’s start against the Wisconsin Timber Rattlers. Mozzicato looked to have turned a corner in his August 15 start, when he pitched five innings, allowing just one earned run with one walk and eight strikeouts. Tuesday, he again pitched five innings, this time allowing two hits, one earned run, and three walks. He struck out seven.

Mozzicato threw 90 pitches in all, 53 for strikes, but one pitch, in particular, caught my eye watching his start. In the bottom of the fourth, Mozzicato was facing Hendy Mendez with a 1-1 count.

Mozzicato’s curveball has always been a loopy, 12-6 offering. This was far from that, with a clear east-to-west ride. For Mozzicato, the addition of his slider gives hitters just one more look and should help keep them off balance. A lot has been made of his fastball velocity, which still sits in the upper-80s to low-90s. He’s still so young that the velocity is bound to improve over some time but it would be nice to have seen some — any — improvement in that department since his pro debut.

The slider should allow Mozzicato to find more success in the meantime and should allow him to be a more effective pitcher even without added velocity. On top of that, his induced vertical break — meaning the pitch is breaking upward from the average level a pitch falls — on the pitch is good which makes it pretty effective as is. It will only be better once the velocity comes.

For the Royals, this is yet another sign of the improvements in their pitching development. The pitching development is light years ahead of where it was just a season ago. Pitchers of yesteryear often debuted with fairly limiting pitch mixes. We don’t need to re-hash the Brady Singer pitch-mix debate, but even others such as Kris Bubic didn’t develop a slider until just this season. For many other organizations, developing an effective pitch mix would’ve likely been a hurdle to clear before they could reach the major leagues.

This is great to see from the Royals and although it’s perhaps been a setback this season for Mozzicato’s performance on the mound, it could catapult him forward next season. The Royals need their investment in Frank Mozzicato to pay off in the biggest way, and this is a great sign that we’re on the right track to seeing that happen some day.