Steven Cruz And His Fastball Dilemma

When you watch Kansas City Royals right-hander Steven Cruz pitch, there are two conclusions we can draw without checking his Baseball Savant page: he has one of the fastest fastballs in the league, but his velocity still isn’t enough to dominate.

Contrary to what Cruz’s 98.4 mph fastball average, the highest of his career and 96th percentile in velocity this season, invokes from the mound, hitters have a clear idea of how to take advantage of his shortcomings. Among the 16 qualified pitchers with at least 45 innings pitched and a 98 mph average fastball, Cruz has the fifth-best Whiff% (29%). Listen to the names ahead of him: Jacob Misiorowski (41.9%), Mason Miller (40.7%), Mason Montgomery (30.8%) and Juan Morillo (30.0%). He has left behind several elite relievers such as Adrian Morejon, Grant Taylor, Andrés Muñoz, Louis Varland, and Abner Uribe.

Opponents have posted a .229 xBA against Cruz’s fastball, and with two strikes, it has accounted for 54.9% of his 51 strikeouts. On that side of the stat sheet, those numbers invoke a display of dominance. However, if we stay focused on that one part, we would not know the inconsistencies that have kept Cruz from making the jump to the first tier of the Royals’ bullpen. When we look at the other side, in reality, his fastball is not as dominant as those numbers suggest.

There have been many situations in which Cruz has solved things with his high velocity, but his 147 wRC+ allowed exposes that his fastball has been more vulnerable in situations where he needs to avoid contact. Its Run Value is -2, and for the third consecutive year, its xSLG has climbed above .400. This year, opponents are hitting .409 xSLG against him, a figure that rises to .475 when the hitter is ahead in the count. The only situation in which Cruz’s fastball becomes unreachable is with two strikes, when opponents have gone 3-for-45, with no extra-base hits, and have struck out (28) in 57% of plate appearances (49).

That said, there is no doubt that the fastball is not Cruz’s most dominant pitch. And that is the Dominican right-hander’s biggest assignment: he has one of the fastest fastballs in the game, but he still has not been able to turn that potential into becoming a dominant enough pitcher. For Cruz, who uses the fastball 55.5% of the time, this presents a bigger problem.

His fastball should be the center of his arsenal and, around it, he should put the rest of his repertoire to work, which is reduced to just two more pitches: his cutter and slider. Fortunately for Cruz, the cutter has become his saving pitch: it has the only positive Run Value in his arsenal (5.0), produces ground balls 54.1% of the time, and the league averages just a 36 wRC+.

The cutter has been his evolving weapon: he has improved its Whiff% to 32.2% this year, and reduced his Perfect Contact% from 28% last season to 18%, well below the 33% he allowed between 2023 and 2024. But there is one important aspect Cruz should work on around the cutter, and it comes as a consequence of an improvement by the opposition in increasing its Over rate to 23%. In 2024, the league averaged 4% against him, and 7% last year.

To a large extent, that anticipation seems concerning, and it is not what usually happens when the hitter takes longer to identify the pitches, which could become an open door to contact.

Part of that problem begins with Cruz’s slider, by far the most punished pitch in his arsenal. Opponents have posted a 157 wRC+ against it, making contact 92.3% of the time within the strike zone. The breakdown hitters are taking advantage of has a lot to do with the slider’s location, especially in the upper third of the strike zone.

That poor history could explain Cruz’s reasonable lack of confidence, as he has lowered his slider usage from 11.1% in 2025 to 4.0% this season when hitters are ahead in the count.

Without a real possibility of his highest-velocity pitch still standing out as his main weapon on the mound, the cutter has taken center stage in Cruz’s arsenal. However, at the same time, it has been overexposed because the slider is far from being a reliable pitch.

That is Cruz’s dilemma. His potential brings us closer to the idea that he has enough to make the jump to the elite level, but the fastball that should drive his arsenal still hasn’t quite done it. The cutter has had to take on part of that role, while the slider’s problems continue to prevent him from sustaining that dominance.

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