Cristian Javier entered his sixth career start, on August 25, 2020, with a simple plan: attack right-handed hitters with four-seam fastballs.
Most rookie right-handers who average 92.4 mph on the pitch would scoff at the idea. And in doing so, most rookie right-handers would be justified. Right-handed hitters across Major League Baseball entered that night with a .399 wOBA against right-handed four-seam fastballs between 92 and 93 mph.
To make matters worse, Mike Trout, all but unanimously regarded as the most feared hitter of the prior decade, loomed on the first step of the dugout with a career .469 wOBA against such fastballs. Although the solution to the seemingly unsolvable problem of facing Trout dodged pitchers for nearly a decade, Javier’s approach seemed, on the surface, to be a pitiful attempt at an answer.
After their first matchup, however, only one player walked back to the dugout without an answer to his problem: Trout. After striking out David Fletcher on four pitches, including three fastballs, and inducing a pop out against Tommy La Stella, Javier stuck to his plan against the world’s best hitter. Javier’s followed his first-pitch inside fastball with a belt-high, in-zone fastball that sailed past the bat of Trout. Recognizing Trout’s aggressiveness, Javier threw both the 1-1 fastball and the 2-1 fastball above the zone, searching for a chase. Trout did not budge.
If Trout thought he earned a fastball in the strike zone by laying off the last two pitches, then he and Javier were on the same page. To Javier, however, that did not seem to matter. Not only was the 3-1 middle-middle fastball that Trout fouled back to the screen a sign that Trout found this matchup uncomfortable; it also was the last chance Trout would have to square up a fastball. Javier, sticking to the game plan, painted a 3-2 fastball at the high-outside corner and strolled back to the dugout as the umpire punched Trout out.
Any doubt that Javier may have had about his approach certainly did not last. In his career, Javier has thrown Trout 69 pitches; 61 of them were fastballs. And just as Javier’s long-term approach against Trout mirrored that of their first matchup, the results followed suit. In their 14 matchups, Trout has gone 0-for-12 with 8 strikeouts, a walk, and a hit-by-pitch.
Generally, a 14-plate-appearance sample may seem too noisy to possess significant external validity about Trout’s offensive profile. Additionally, despite Trout and Javier’s division rivalry, Trout’s season-long production is hardly contingent on his production against Javier. But the how behind Javier’s success, combined with recent signs of mortality from Trout, begs the question: did Javier find a solution to the Mike Trout problem?
Javier’s Fastball
Despite its pedestrian velocity, Javier has made a living off his fastball, although its recently popularized nickname “the invisiball” is a more appropriate label, at least from the perspective of opposing hitters. The pitch ranks fourth among four-seam fastballs in Run Value since the beginning of the 2020 season, thanks primarily to its deceiving shape. Specifically, the flatness of the pitch yields a rising effect that induces swings under the “disappearing” baseball when located high and called strikes when located low.
Among sabermetricians, the scientific description of Javier’s fastball revolves around the concept of Vertical Approach Angle. According to Alex Chamberlain’s Pitch Leaderboard, Javier’s four-seam fastball has a career Vertical Approach Angle Above Average––a location-adjusted measure of Vertical Approach Angle––of 0.48 degrees, placing itself among the flattest fastballs in Major League Baseball.
Although there are a few different ways to generate a flat fastball, Javier’s is crystal clear. His ability to generate extreme backspin relative to his release height creates a unique amount of induced vertical break (IVB) from an approximately three-quarters arm slot. The induced vertical break gives the rising effect that forces whiffs at the top of the zone and called strikes at the bottom.
Against Trout, Javier has taken advantage of locations near or above the top of the zone, which only adds to the flatness of the pitch. Of the 61 fastballs he has thrown Trout, 19 were in the upper third of the zone, and 26 were out of the zone but above the vertical center of the strike zone. Those 45 pitches featured 17 swings and just a single ball in play: a weak pop out to the first baseman.
The Beginning of Trout’s Decline
After posting ten consecutive seasons with a Weighted Runs Created Plus (wRC+) of at least 160, Trout’s 2023 wRC+ sits at 132––a mark reflective of a great hitter, but not the superstar we have come to know. Additionally, once Trout was revealed to have a chronic back issue significant enough to persist for the remainder of his career, a continuous decline from stardom entered the realm of possibility.
In 2020, Trout’s struggles against Javier could have been brushed off as a mere matchup nightmare. However, as these struggles have continued into 2023, amid the first true signs of a decline for the future Hall of Famer, one plausibly may hypothesize the extent to which his prevailing inability to hit Javier’s fastball stems from a root cause similar to that of his overall decline.
To identify the exact causes of Trout’s struggles against Javier’s fastball––and more importantly, the alignment of their progression with Trout’s general decline––we can analyze his results against the three aforementioned contributors to Javier’s fastball success: pitch location, induced vertical break, and release height.
Trout’s Production Against High Fastballs
Against fastballs above the middle of the strike zone but out of the zone, Trout excels, primarily due to his superb plate discipline. His Run Value per 100 pitches (RV/100) was 4.37 in 2022, and it is up to 4.63 in 2023, on par with his career numbers.
Trout’s performance against high in-zone fastballs, however, tells a much different story. As displayed in the table below, Trout has declined significantly against these fastballs, posting the two lowest RV/100 marks of his career, with a minimum of 50 pitches.
Trout’s steep decline against upper-third fastballs, juxtaposed with his lack of a decline against out-of-zone high fastballs, suggests that his struggles against high in-zone fastballs stem from a decline in his swing quality, not his plate discipline.
… With a High IVB
Although Trout’s 0.36 RV/100 against four-seam fastballs with at least 15 inches of IVB is among the lowest in his career, both his 2022 and his 2021 values fell within the top five seasons in this department in his career. Therefore, on the surface, Trout does not seem vulnerable against high-IVB fastballs.
However, the narrative changes when focusing explicitly on the location of fastballs at which Trout struggles: upper-third fastballs. The table below reveals a drop-off in RV/100 similar to the decline in the previous table. The primary difference in this table is that Trout has struggled more in 2023 than in 2022, suggesting that Trout’s wRC+ drop-off this season may be especially related to a change in his ability to produce against high-IVB, upper-third fastballs.
… From a Low Release Height
Although many pitchers can throw relatively high-IVB fastballs in the upper third of the zone, just as many pitchers throw from an approximately three-quarters arm slot, few are able to do both; Javier, as previously established, is among the few. Thus, the following table, which shows Trout’s production against low-arm-slot, high-IVB, upper-third fastballs, is especially relevant to Trout’s production against pitches like Javier’s fastball.
As shown in the table above, Trout’s decline against such fastballs is on par with his decline before we factored in release height. However, it is worth noting that the magnitude of the values is even lower than before, indicating that pitchers like Javier are even more likely to succeed than mere high-IVB, high-locating pitchers.
Altogether, although Trout’s struggles against fastballs increase when filtering for IVB and release height, the drop-off begins when considering upper-third four-seam fastballs. For Trout, this truth is worrisome, as Javier’s fastball location is the most replicable quality of the pitch. Though other pitchers may have a flat enough fastball to excel against Trout to the extent that Javier does, targeting the upper third is at least the beginning of a game plan that once seemed unattainable.
However, despite the perceived alignment between Trout’s general decline and his decline against Javier’s fastball characteristics, the ability to find a root cause to confirm or deny their alignment is contingent on more precise data, such as swing path data. As previously mentioned, Trout’s drop-off has come primarily on in-zone pitches, thus suggesting a swing quality decline. However, without any empirical evidence of a swing quality decline, such a cause remains purely theorized.
Nonetheless, the empirical validity of their alignment is far from negligible, as Trout’s decline has coincided with proliferating struggles against Javier’s fastball traits. Until Trout reasserts his ability to compete against upper-third fastballs––especially those with a particularly flat shape––opposing pitchers can begin to hypothesize solutions to the long-lasting Mike Trout problem.