I agree with you on the DM.
Even when Fofana was in-form in the first half of the season (I'm not sure if he's that guy or the guy who collapsed after January) we still conceded bad goals, both under Fonseca and under Conceicao. We are not one Rodri away from being a fundamentally different team.
But where I disagree with you is that many of our adjustments are tactical from first halves to second halves. Conceicao seems to be very good at making adjustments, but he seems insanely bad at setting up a team to start.
When I look at the goals we conceded in the first ten minutes (I went back to watch [I missed them live]) you can see a cascade of problems in our midfield and attack, giving away possession whilst we are in transition. Musah is doing too much, trying to be something more than he is, and while when his dribbles come off, he creates havoc for our opponents--before he then messes up the pass or cross lol--but when the pass or move doesn't work, he's taking those risks at bad times.
Jovic, when you take away his goal, was average, sometimes below average (compared to his impact usually) but once he got going, holding up the ball, not losing it, and connecting play, we started to look much better. Pulisic doesn't do this, the usage of Pulisic centrally makes him far less effective and both Fonseca and Conceicao keep going back to it and it hurts Pulisic and the team.
Jovic was doing what I thought would be bare minimum for Felix, but with Musah thinking he's some attacking force (rather than being a shield or to just put out fires) and with Pulisic being played more centrally, we collapse. These are tactical choices that other teams are identifying and exploiting.
I don't think we are conceding shit goals in the first half and then fighting tooth-and-nail in the second half because they don't give a shit. I think Conceicao is setting up the team very poorly to starts games, consistently.
If Fonseca gets negative points because he had a pre-season, whilst Conceicao gets "excuse points" for taking over mid-season without a pre-season... then you could say that Fonseca (seemingly) had less impact on our transfers than Conceicao did, since Conceicao seemingly got the players that he wanted: Walker, Gimenez, (who knows about those two, to be fair) but most importantly: Felix. Was Felix a Mendes thing? Or did Conceicao really want him? I dunno.
I think a lack of a pre-season hurts a manager more, taking over mid-season, even if you get some Man City-like transfer window in January is still much harder than in the summer--but what mystifies me is how Fonseca and Conceicao both drift towards a 424-like shape, where we have not had a true CAM to make that system work. Hell, Fonseca uses Tolisso in that CAM spot (sometimes as a Hakan-style "LAM") which is far more solid than what he did here. When we push Reijnders up there, we don't have anyone to connect play from deeper, and when Reijnders is further back (where I think he's best) we then don't have anyone to take that advancement to build coherent play, and Pulisic doesn't do that at the CAM spot.
I'm at a point where I think our analytics team forces our managers into playing that 424-style 4231 on our managers. I am at a loss for words, otherwise. Why are we going to a shape that has been exploited by opponents, big and small, time and time again? The only time our 424 has really worked (with Felix) from the start is the first half against Feyenoord, where we looked... genuinely impressive. Then Theo got that stupid card, etc. But other than that, it doesn't matter if we're playing Napoli or Lecce, the setup isn't working.
We don't have a Musiala or some Leao-level mercurial talent at CAM, I hated playing Brahim at CAM, but if we could have him right now, I'd bite your hand off (I like him more as a RW). But we don't even have that, so why do we keep going to this?
I don't get it, because in order to solve the CAM problem, we create new problems in other places: Reijnders at CAM? Who will conduct and connect play centrally to advance the ball and control possession? Okay, fine, Pulisic at CAM? Where is our width on the right to stretch a team out, plus Pulisic is far less effective there (at CAM), and then we have to deal with the errors or lack-of-danger from whoever we play at RW, Musah, Chuk, Jimenez, which then allows teams to choke out our left side.
The players are fighting in the second halves of games, and quite frankly, they were working hard after that initial shock of being down 2-0 in ten minutes against Fiorentina--why Conceicao has abandoned the more cautious starts to games that colored his initial success, I don't know.
Yes, players need to try hard--but when you're asking someone like Musah (who I like) to do things outside of his skill-set, you're asking for problems. When there are no outlets for pressure, we can't build play, all we do is hit it to an attacker and hope they can create space through individual skill. This is where I think our squad construction issues come up: our midfield is the worst unit, by far. Outside of Reijnders, you have an inconsistent Fofana, but we have no backup for Reijnders, no one who can share the creative load with Tiji, and our replacement midfielders are Musah, Bondo, and RLC. Oh, and Terra. That's our midfield unit. Bondo might turn into a good player, but he's not that now, he's not even a Meite-level player now.
So I'm not saying it's only one thing, but to me, there's a problem in our personnel, there's a problem in who we decided to rely on (Felix or forcing Pulisic at CAM when he's our best RW by far), and that we lost a tempo-setter in Bennacer and didn't replace him. Bondo is a more defensive Musah, they both make mistakes and RLC has only played 1,000 minutes this season--so, for me, it's more about a very flawed midfield unit and two managers who continued to push the same failed system that got Pioli fired, because if they have the fight in the second half, even when the season is clearly lost (we're probably finishing 9th, maybe 8th?) if they're still running and fighting to get back into games, doesn't that show they aren't these terrible people, but rather, there are other issues at play?