He was all the way down at 69 for FanGraphs headed into the season and up to 43 now.
Here is their reasoning:
https://blogs.fangraphs.com/boston-red-sox-top-47-prospects/
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My offseason report on Mayer was filled with apprehension about his issues against secondary pitches (which for a couple of years he had performed in spite of) and the way he was trending athletically on defense. It also acknowledged that some of Marcelo’s late 2023 dip could have been caused by the effects of a shoulder injury (which he tried playing through before it ultimately ended his season), and that a 21-year-old could pretty quickly remake his body and once again have the requisite athleticism to handle shortstop. Some of that has turned out to be true, and Mayer has raked at Double-A Portland during the first half of 2024, but I still think there are some underlying issues here. Clearly he’s graded as a 50 FV player and therefore projects to be an everyday shortstop, but I think these warts will stifle his production below the superstar level readers might expected of him.
The way Mayer’s swing works (his front side is very upright through contact, his hips tend to bail toward first base pretty early, and his bat path struggles to find pitches down and away from him) continues to leave him vulnerable against soft stuff. His issues haven’t been as stark in 2024 as they were in 2023 when he had a sub-.500 OPS against secondary pitches, but there’s still an enormous dip compared to the way he handles fastballs. Choirs of angels have blessed Mayer’s hitting hands, which are deft and drive contact explosive enough to remain excited about his overall offensive future, just not to the level of a
Bobby Witt Jr. or
Corey Seager in terms of impact. If we suddenly see more bend in his lower body, the way
Max Muncy altered his swing before his huge breakout in LA, then there will be reason to re-evaluate.
Mayer has always been a bit boxier than the usual elite shortstop prospect, but his hands and actions are so skillful and polished that he seemed likely to play there despite middling range. Perhaps because his mobility was compromised from the general discomfort of his shoulder issue, Mayer’s range backed up in 2023 and his arm accuracy was sometimes poor. He definitely looks trimmer in 2024 and the Red Sox appear to be positioning him closer to the hole so he can make more plays moving right to left. It isn’t sexy, but it works. Mayer’s footwork and actions are still very polished and the Red Sox have found a way to mask his mediocre range and arm strength (for shortstop). Things feel much more stable here than they did at the end of 2023. Hopefully Mayer will keep hitting Eastern League pitching and merit a promotion so we can watch him face and adjust to junkballing Triple-A veterans who might force him to make relevant adjustments. He’s tracking like a late 2025 or early 2026 debut.
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