If you're being coached with weak instruction, or left to figure things out yourself, some are going to be on island because they *need* instruction and coaching and are, quite frankly, incapable of being these cultured thinkers who can digest and process a game in real time. Honestly, sometimes it's giving the players too much respect to have them go out there and freestyle; that's for the brilliant, like when Real Madrid were doing their thing and winning CL's with moments of unquestionable, individual brilliance whilst having that free rein to express themselves as they saw fit.
I'm not knocking players for not being skilled free-thinkers, either. Some players are brilliant under instruction and absolutely dogged once given their brief - I'll take that all day. A good example would be McTominay. His best actual form and performances in our shirt was in the McFred partnership when his one and only job was to sweep up behind Fred and then give the most simple pass to another red shirt. He didn't have to think about spatials or positioning, or covering or tasking himself with expansive passing and he absolutely thrived just being Fred's water carrier. It can seem undignified, but it extracted all of his energy and reduced aimless or clueless actions to naught. He wasn't trying any more or less, but his energy was very easy to harness and be of value in that simple role. Make McTominay a freer thinking midfielder, and the accusations of ball-watching and not covering bodies etc. etc. come thick and fast. He's still the same guy, and he isn't trying any more or less.
I think our squad is devoid of confidence and a lot of them can't navigate through torrid times; if your confidence is on the floor you're going to be stuttery and apprehensive, which compounds the misery. You've highlighted this in your post as downing tools, but I'd more say that's a collective who don't know what to do with themselves where downing tools is purposely putting half-arsed effort into everything you're doing, and even purposely passing the buck because why not, who cares? I don't think our players phone it in in this manner; they're just not very good, but they're trying.
Dalot is another good example, I think. He is wildly erratic from game to game, but he's not trying any more or less, it's just his level of ability.