The curious case of Michael Lorenzen

The Royals have seen three different versions of their number five starter in 2025

When the Royals signed Michael Lorenzen during the offseason, there wasn’t nearly as much celebrating in Kansas City as there was when they signed Seth Lugo, Michael Wacha, or Michael Wacha the second time. But there were some quiet nods of approval. Lorenzen, it was assumed, would be a more than adequate fifth-starter or swingman option for the Royals, able to pitch with reasonable effectiveness in the rotation and perhaps could turn things up in the bullpen if young Royals starters like Kris Bubic and Alec Marsh proved capable of taking the next steps in their careers.

Unfortunately, Marsh was hurt before the season could even start and has faced numerous delays to his recovery since then. What many initially hoped would be a short-term injury, keeping him out a couple of weeks at most, has lasted the entire season to this point. Kyle Wright, who many hoped would serve as rotation depth at worst and potentially more, has likewise dealt with multiple setbacks to his return. He was activated from the injured list and demoted to AAA Omaha, but has been injured again and hasn’t been able to pitch since June 21. Seth Lugo and Cole Ragans have dealt with injuries, and the team worries about Kris Bubic’s innings load as the season goes on. Fortunately, Michael Lorenzen has been a rotation stalwart all season alongside Michael Wacha and surprising rookie Noah Cameron.

The Royals have seen three different versions of Lorenzen this year, each lasting six starts to this point. Royals fans went from extremely grateful to have him on the club, to begging for him to be demoted to the bullpen or cut, to grateful to have him again. (At least until an injury sidelined him over the break.) What changed to get him back on track?

The Good Lorenzen (Opening Day - April 29)

3-3, 3.48 ERA, 4.50 SIERA, 10.3% K-BB%, .287 BABIP, 79.2% LOB%, 28.6% Hard Hit

You can find how to read the chart below in my article about Bubic, here.

Lorenzen’s pitch mix started the year much like it was last year; he led the way with his fastball, threw a heaping helping of changeups, and mixed in the rest of his pitches as necessary. He particularly leaned on the curveball and changeup against lefties, while righties were more likely to see the sinker and cutter. That makes a lot of sense with changeups and curveballs generally being better against opposite-handed hitters while cutters and sinkers do better against same-side hitters.

There were two rather stark issues here that Lorenzen was able to avoid getting in trouble with, but will come up later. His fastball was getting hammered, and he wasn’t getting any chases or whiffs on his changeup.

You can also see he was getting perhaps a bit lucky with a very high strand rate; the average strand rate, which most pitchers revert to over time, is 70-72%. Lorenzen has a career LOB% of 74.4%.

The Bad Lorenzen (May 4 - June 3)

0-3, 6.89 ERA, 4.24 SIERA, 13.4% K-BB%, .343 BABIP, 64.3% LOB%, 37.4% Hard Hit

You can see in this second stretch of eight games, which starts with five runs allowed in 4.2 innings to Baltimore and ends with seven runs allowed in 2.2 innings to St. Louis, Lorenzen was both bad and unlucky. His fastball was somehow hit even harder. His changeup started getting chases and whiffs, but when they connected with it, they hit it a lot better. His curveball was being absolutely destroyed when they could connect with it. A 37.4% hard hit rate is just abysmal. You might think the BABIP and LOB% are unlucky, but when a pitcher is getting hit that hard, it’s reasonable to think he was actually just bad.

To be honest, I expected to see something change in the metrics of his fastball to lead to this scenario. But the spin and break rates all appear to be pretty similar. In fact, it gets the exact same rating on the tjStuff+ scale of 97, slightly below average. The best I can figure is that hitters started knowing when he was going to throw the fastball, either because he was tipping pitches or because he just relied on it in the same counts too often. They basically stopped chasing it and almost never missed it when they did swing. If you throw one pitch a quarter of the time and every hitter knows that pitch is coming, they’re going to crush it. Especially when that pitch is a straight fastball without particularly good movement or velocity numbers to back it up.

The Best Lorenzen (June 8 - July 6 and beyond?)

2-2, 3.63 ERA, 3.98 SIERA, 16.2% K-BB%, .231 BABIP, 75% LOB%, 30.2% Hard Hit

As you can see, there was a drastic change in his pitch mix starting on June 8, which was a win against the Chicago White Sox during one of the most brutal stretches of the season for the Royals. He started leaning on his sinker much, much more. He increased its usage to both sides of the plate, but tripled how often he threw it to lefties. Lefties were the biggest offenders during his worst stretch, which is very weird for a changeup specialist who has not really had much in the way of handedness splits in his career.

He also started getting much better results on the sinker. You can see in the above chart that not a lot changed with the pitch’s spin, but he shifted his arm angle to be much more vertical. This appears to have resulted in an increase to the induced horizontal break on his sinker by one inch from the bad stretch while maintaining a one-inch decrease of the induced horizontal break from his changeup from the first section to the third. This differentiated the pitches enough that where in the first two sets, they were landing in almost identical places, they’re now clearly aimed in two different areas, even if there is some overlap. The difference in pitch movement has made both of them drastically better.

There’s been an add-on effect with his fastball playing up now that it’s being used less. The cutter is also working better than at any other point in the season. It’s easy to look at the ERA and say he was better in his first six starts, but look at the LOB% and SIERA as compared to that first set. Not to mention the K-BB%. The ERA doesn’t necessarily reflect how improved his process has been, but the numbers say that what he’s doing right now is much more likely to sustain him if he can keep it up whenever he retakes the field.

If you’re ever tempted to think of professional baseball as a “kid’s game”, you should come back and review this. Michael Lorenzen changed his arm angle by four degrees, which shifted two of his pitches an inch or so, and he went from batting practice to upper-mid-rotation starter. Is it any wonder so many guys fail to ever make the big leagues despite promising high school, college, and even minor league careers? The tiniest details can make a huge difference.

One thing has become clear: if the Royals are going to continue their July turnaround, they’re going to need Lorenzen to make a quick comeback. Here’s hoping he can pull it off.