A few thoughts:
-Alvarez’s numbers are down slightly but not tremendously off what he did in past years. And he too of course also was hurt (as he seems to be every year). Even if he finishes with a .718 OPS/101 OPS+, that’s not necessarily bad for a catcher; it’d be among the top third (or better) across MLB. It’s just not superstar numbers. And while he’s been hurt every year, there hasn’t been significant signs of improvement year over year. Of course, he’s still just 24, but is Alvarez just “ok” and not a star? It may have nothing to do with approach/philosophy.
-Both Baty and Vientos had some awful years under prior coaches so it’s not as if this year is something out of the blue. Baty might be a bit more concerning as his peak was last year (so did a new philosophy this year cause a backslide?) but Vientos already significantly backslid from 2024 to 2025 without anything changing in terms of coaching/philosophy/etc.
-Bichette is a long-established hitter and as noted has improved over an abysmal start to the year. Was it bad philosophy that contributed to that underperformance or was it bad luck/a tough adjustment period?
I raise a few of those points somewhat as devil‘s advocate, since I’m generally in favor of a wholesale firing of the coaching staff anyway. But I’m not sure it was really a flaw in approach that did the Mets in versus some bad luck* and an absence of sufficient depth on the roster.
*As I have probably said before, coming into the 2026 season, Bichette, Soto, and Lindor would have started for just about every team in MLB. They combined for 15.5 WAR in 2025 but 4.6 in 2026. Flip 11 wins for the Mets and they’re at 73-65, in position to get a wild card, highly problematic pitching staff notwithstanding.