It's like that in EVERY pro and now college sport. If a guy goes 4 of 10 from the foul line in a game and you lose by 1, fire the coach. The kid shoots 500 a day, makes 425, but once the bright light turn on and the heart starts racing ....clank. Coaches fault.
The kicker misses two field goals and an extra point. Fire the coach.
Can't get rid of the guaranteed deals and guys who sell merch.
In the Mets case, the GM let's Alonso walk out the door, spends their money in 10 other places, goes nuts on the Soto deal, spends a fortune on Semian and now the new 1B can't field routine ground balls, leading to losses, so....fire the coach. The GM who gave the guy the cards to play carries absolutely no culpability.