Five Royals Pitchers Who Have Stood Out This Spring, Based on TJ Stuff+

[Kevin O'Brien]

Image courtesy of Denis Poroy-Imagn Images

When it comes to evaluating pitchers and their pitches, pitch modeling is all the rage. Whether it's models from Eno Sarris (Fangraphs), Jeremy Maschino (Pitch Profiler), or Kyle Bland (Pitcher List), pitching models give us a chance to understand how the characteristics of a pitcher's particular offering contribute to preventing runs. 

Thomas Nestico's pitch model, TJ Stuff+, has been one of my favorite models, mostly because I believe in the data he selects and analyzes. Furthermore, TJ Stats' presentation of the data, especially through his pitcher summaries, makes the most sense to me for understanding pitch effectiveness. When it comes to what TJ Stuff+ does, there are three key characteristics: 

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• tjStuff+ is a metric that calculates the Expected Run Value (xRV) of a pitch
• tjStuff+ normally distributed, where 100 is considered average, and the Standard Deviation is 10.
• tjStuff+ is provided for individual pitch types (min. 10 pitches), as well as the pitcher as a whole (min. 10 pitches)

A full deep dive into the TJ Stuff+ process is available in this Medium article published by Nestico in 2024. 

With that context about TJ Stuff+, Nestico's TJ Stats site has seen massive improvement over the past year and has been one of the best resources this spring for acquiring and breaking down pitch-modeling data from Spring Training. With every MLB Spring Training ballpark having public Statcast data, fans can get a breakdown of pitcher TJ Stuff+ every outing and overall this spring as well. 

Thus, with Opening Day coming up in 10 days, I wanted to see which Royals pitchers have been the top performers this spring in TJ Stuff+, whether in Cactus League play or WBC competition. A full leaderboard of Royals pitchers and their TJ Stuff+ marks can be seen here.

Let's take a look at five Kansas City pitchers who have thrived this spring in TJ Stuff+ and what Royals fans can take away from those particular pitchers' metrics in preparation for the upcoming season. 

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Steven Cruz, RHP, 107 Overall TJ Stuff+

Cruz hasn't seen a whole lot of work this spring, as he has only pitched 4.2 innings and thrown 56 total pitches. However, in his limited work, the 26-year-old righty has been sensational on a TJ Stuff+ end.

The 6'7 pitcher leads all Royals with a 107 overall TJ stuff+ mark this spring. That includes two pitches with TJ Stuff+ marks of 110: his four-seamer and slider. His four-seamer has been his best pitch not just in terms of velocity (96.6 MPH), but also whiff rate (70%) and xwOBACON (.274). The pitch has shown some growth for Cruz over the past year in generating better iVB while still maintaining the horizontal break (HB) that makes it a unique fastball offering. 

When he locates the four-seamer effectively in the zone (especially up), it can be an effective offering, especially in two-strike counts. Here's an example of Cruz pumping the four-seamer 101.2 MPH last year to Cal Raleigh and striking him out.

His slider has also been an effective offering in terms of TJ Stuff+ and zone rate (58.8%). He hasn't generated as many chases (28.6%) or whiffs (18.2%) with his primary breaking offer, but he may still be working on the command of the pitch this spring. I think once he gets more ramped up, his slider will be an effective secondary offering for him. Last year, he produced a 24.5% whiff rate and .201 xwOBA on the slider. 

The only pitch that has been underwhelming is the cutter, which has a 99 TJ Stuff+.

Cruz has been flooding the zone with the offering (69.2%), but it's been getting hit hard (.691 xwOBACON). The cutter was a great put-away pitch for him last year (36.4%), but it wasn't a great overall whiff pitch (19%). His cutter was his second-most-thrown offering last year (25.5%), so I wonder if Cruz will throw his cutter less and slider more in 2026, based on his Spring Training trend. 

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Cole Ragans, LHP, 104 Overall TJ Stuff+

Ragans has been the Royals' second-best pitcher in terms of overall TJ Stuff+ and the best starter this spring in this category. He has four pitches with a 100 TJ Stuff+ or higher, including his four-seamer, slider, changeup, and cutter. He also has three pitches with 60 grades or higher (four-seamer, slider, and changeup). 

His four-seamer and slider have been his main weapons in Cactus League play, as Ragans has thrown them 53.4% and 18.7% of the time, respectively. His four-seamer is generating a 30.2% chase and 37.7% whiff, and his slider has a 47.8% cahse and 43.5% whiff. The four-seamer has gotten hit a bit hard, with a .535 xwOBACON. That said, it's Spring Training, and Ragans' command is still getting ramped up (46.6% zone rate). 

Ragans generated a 43.4% whiff rate and 28.9% put away rate on his slider in 2025. He threw it only 13.8% of the time last year, nearly 5% lower than his usage this spring. When the slider is working, it's his best swing-and-miss offering, as illustrated in this strikeout of Austin Hedges last year. 

He's only been using the knuckle curve sparingly this spring, with an 8.8% usage. That's four percent down from a year ago. However, it only has a 97 TJ Stuff+ and a 40 grade, so it makes sense why Ragans would opt for the slider more and the curve less in Arizona. It will be interesting to see if this usage breakdown carries over to the regular season.

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Ryan Bergert, RHP, 102 TJ Stuff+

The results haven't been great for Bergert this spring. After a strong start, he has a 6.52 ERA and 1.45 WHIP in 9.2 IP. To make matters worse, his FIP is worse than his ERA at 9.46. That doesn't bode well for him getting a spot on the Opening Day, though Spring Training numbers always have to be taken with a grain of salt.

On a positive note, the stuff has been solid for Bergert in Cactus League play.

He has an overall TJ Stuff+ of 102 with four pitches with TJ Stuff+ marks over 100 (four-seamer, slider, sweeper, and curveball). He also has a chase rate of 36.5% and a whiff rate of 34.7%. What's interesting, however, is that despite those strong chase and whiff numbers, he has a pretty mediocre K% (19%). Thus, putting away batters has been a work in progress for Bergert this spring. 

An issue is that Bergert's control has been erratic, as evidenced by his 43.5% zone rate. One concerning pitch related to this trend has been his slider. It has a 106 TJ Stuff+ and some great chase (45.2%) and whiff (54.8%) rates. However, it has a 42.6% zone rate and .497 xwOBACON. A primary issue is that it hasn't been all that effective against lefties this spring, according to his heatmap data from TJ Stats. 

The slider has a 52.8% CSW and 80% whiff rate against righties. However, it has only a 16.7% CSW and a 9.1% whiff rate against lefties. He is also leaving the pitch a lot more in the zone against righties, which explains why he's not generating as many whiffs. Bergert has thrown the slider 19.6% of the time against lefties this spring, so it is used fairly often.

Hence, ironing out the command on the pitch to generate more strikes, especially of the whiff variety, could make his slider more effective overall in 2026 (and thus help his strikeout problem in Spring Training). 

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Dennis Colleran, RHP, 102 TJ Stuff+

Colleran has been one of the best non-roster invitee stories this spring for the Royals. In four innings of work in Cactus League play, he posted a 0.00 ERA, 0.25 WHIP, 1.65 FIP, and a 25% K% and K-BB%. When it comes to results, no NRI pitching prospect was more impressive than the former Northeastern product. 

In terms of TJ Stuff+ data, there was also a lot to like with Colleran this spring.

The 22-year-old righty posted a 102 overall TJ Stuff+ with a 55.2% zone rate, 30.8% chase, 33.3% whiff, and .241 xwOBACON. All those metrics are not just above-average, but quite stellar. Even though Colleran was already sent to Minor League Camp for the remainder of Spring Training, he may be a candidate for a midseason or end-of-year call-up if he progresses in Minor League ball as expected in 2026. 

One of Colleran's most intriguing pitches was his four-seamer, which he threw 34.5% of the time this spring. The four-seamer averaged 98.2 MPH and had an excellent chase rate (33.3%), whiff rate (45.5%), and xwOBACON (.277). However, the TJ Stuff+ was mediocre at 99. 

When it comes to shape, Colleran's four-seamer is pretty atypical. It has more horizontal movement with a 12.7 HB. As a result, his iVB is lower than typical for a four-seamer, at 11.6. Colleran has a pretty horizontal arm angle at 19 degrees, so increasing the iVB should be possible. However, it's a bit flatter, moving more like a sinker than a traditional four-seamer. 

Here's a look at the heatmap data of Colleran's four-seamer, and it's interesting to note how much he left it in the zone this spring.

Now, the middle location of those four-seamers didn't hurt him too much. He had a 33.3% CSW against lefties and 50% CSW against righties, as well as xwOBACON marks of .321 and .263, against lefties and righties, respectively. However, when it came to the quality of competition, he had an Opponent Quality of 6.4, according to Baseball-Reference. That is just below Double-A competition on their scale.

Thus, Colleran still has some things to work on, especially with his four-seamer. The velocity is there. The swing-and-miss ability is there. However, generating a better shape on the pitch will help him in his transition to the Major Leagues, whether it's this year or next. 

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Luinder Avila, RHP, 102 Overall TJ Stuff+

Avila has been one of the more intriguing pitchers for the Royals this spring, as his outlook for 2026 still feels a bit in flux. 

On one hand, it seems that Matt Quatraro and the organization believe Avila can still develop into a frontline starting pitcher at the MLB level. If that's the case, then it would make sense for Avila to begin the year in Triple-A Omaha so he can get starts and innings. That's hard to do now at the Major League level with a crowded Royals rotation.

However, looking at his repertoire and TJ Stats summary, it's hard to fully buy into Avila as a starter for now.

The Venezuelan-born pitcher has an elite curveball that demonstrated a 107 TJ Stuff+ and a 66 grade this spring. He had some trouble with locating it in Arizona, as evidenced by his 38.6% zone rate and 18.5% chase. However, he still had a 35.7% whiff rate on the pitch, which shows its effectiveness at generating swing-and-miss swings.

The big area of focus with Avila is his fastball offerings, specifically his sinker and four-seamer. The pitches have average grades, with his sinker at 96 TJ Stuff+ and his four-seamer at 101 TJ Stuff+.  That said, despite having a lower TJ Stuff+, this sinker has been more effective this spring for Avila, as he is generating a 37.5% chase, 35% whiff, and .171 xwOBACON with the pitch. His four-seamer has a better TJ Stuff+ but lags in whiff (15.4%) and xwOBACON (.627). 

What's intriguing about Avila's sinker and four-seamer is that when he's fully letting loose of it in high-pressure situations, like the WBC, he has seen a sharp jump in pitch quality. That was the case in Monday's WBC semi-final, as he went 2.1 IP and posted excellent stuff metrics in his relief appearance against Italy. 

Not only did Avila have a 106 overall TJ Stuff+ against Italy, but he had three pitches with grades over 70 (curveball, changeup, and four-seamer), and all of his pitches were over 60. He didn't generate a lot of whiff (11.8%), but he did a solid job when it came to inducing chase (38.9%) and weak contact (.291 xwOBACON). 

Thus, would Avila be better served in the bullpen, where his stuff could play up in the big, high-leverage moments? The data seems to point in that direction, though the decision will ultimately fall on Quatraro and GM JJ Picollo. 

Safe to say, after a strong MLB debut in 2025 (1.29 ERA and 0.93 WHIP in 14 IP) and a strong spring in the Cactus League and WBC play, it will be tough to leave Avila off the Royals' Opening Day roster. 

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