If one of the main complaints is "unaware of game situations" then who bears the responsibility of coaching them in that game situation? The base coaches. I get what you are saying and agree to an extent, but in game play falls on the shoulders of base coaches in that moment, which is probably why they have had 3 in 3 years at first base. I get that some blame falls on Cora because he is the head guy, but having fundamentally sound base coaches is more key IMO. That's what they are hired to do.
I agree to some extent, but preparing both the base coaches and the players for what is going to happen on the field of play is the responsibility of the manager, in my opinion. Cora has been talking about "fundamental baseball" heading into spring training since the day he arrived, and whatever kind of schedule/drills/training he has put into place over five seasons in the spring is either not effective, or not translating onto the field for some reason.
For what it's worth, "fundamental baseball" to me means everything that happens from the time the pitcher starts his windup, from a player's secondary lead until the umpires signal that the play is over or dead, and it includes both offense and defense.
This team has failed in many, probably most, and, in my opinion, something pretty close to all aspects of fundamental baseball over at least the last two seasons, and really the last five (keep in mind that after the hot start in 2021 the team totally stumbled down the stretch and did not appear prepared for the rigors of a pennant chase, before eeking in on the final day and being Kiké Hernandezed to within two games of the World Series).
That baserunning and defense chart that
@absintheofmalaise posted above is depressing enough, but watching it play out in real time is even worse. It isn't just getting thrown out taking extra bases, it's not taking an extra base when you should. It's not just caught stealing, it's putting your team in a bad spot when stealing at an unnecessary time, or doing it recklessly. It's not just errors, it's not being in the right place to put your team in a spot to make a play, or making a throw that shouldn't be attempted. It's not just routine plays, it's reacting when something goes awry, like a bad hop or a player on the other team doing something unexpected (and other teams know they can execute out of the ordinary plays against the Red Sox because they have watched them fail to execute during them for the last five seasons). There is not a lot of "coaching" going on during the plays, and so it is incredibly important for the players to be ready for any situation that could occur before the play starts.
It takes one game of watching, say, the Rangers (or the Braves, or the Diamondbacks, or the Mariners, or any number of other teams) execute the "little things", to recognize that there is something fundamentally wrong with how the Red Sox on the field have been run since 2019.
It's not all on Cora, the organization and, yes, the base coaches, all have some of the blame. But Cora is the one who should be leading the way and figuring out ways to help the players perform at the best of their abilities, and I do not believe that this has happened under his tutelage.