This is from the McTominay thread but it's more relevant here. It would be nice to actually discuss tactics here instead of arguing with knee jerk reactions about results and non-descript criticisms.
I had the exact same question as the post you replied to while watching the game, as McT was hard to spot all game. Is your understanding we set up like this?
———————Højlund———
——Rashford———————
——————Bruno—————
—Eriksen————McTominay
————Casemiro—————
Reguilon-Licha-Linde-Dalot
—————Onana—————
Cause while i give some of the blame to McT for being invisible, and also players like Case and Licha for having a shit day at the office, if EtH is changing his setup at home instead of drilling his preferred system, he is soon gonna be in trouble. I can be very loyal and patient supporting a man with ideas who has promise, but hasn’t delivered yet. But if he himself starts to doubt, why should we believe?
I think ETH changed the tactics here for 2 reasons. The first is that he's probably reacted to our midfield getting outnumbered and easily played through, and the second is that with Antony and Sancho were unavailable to play at RW and Mount, Amrabat and Mainoo unavailable to play in midfield. He doesn't trust Pellistri to start at RW and he didn't want to play the usual 4-1-2-3 tactics with Bruno at RW because that would leave McTominay and Eriksen as the lone central midfielders (which we can all agree would have been an obvious disaster).
Out of possession, with Brighton playing from the back, he had Hojlund and Rashford play narrowly with Bruno in between slightly further back to take away the middle of the pitch. The midfield three played a bit wider behind them. I think the goal here was to force Brighton into playing out to the side, then sealing them tone side of the pitch clamping down and stealing the ball. This largely worked, as Brighton struggled to move the ball through the pitch for most of the match and we generated a lot of attacks from stealing the ball and counterattacking. The problem was Rashford and Hojlund didn't do much with their opportunities and Brighton got 3 easy goals out of the 4 or 5 opportunities they created because the midfielders didn't track Brighton's midfield runners into the box.
So yeah, IMO there was a tactic there and the players broadly executed it. The problem is with the problem seems to be with workrate and individual skill and decisionmaking. The workrate thing is probably difficult to fix without alternate players to compete with the starters and the skill and decisionmaking is going to involve players getting reps and learning through mistakes.
If this is still happening in February it could be worth questioning the manager but there are still a number of players who've had this exact problem of workrate and decision making with Mourinho, Ole and Rangnick, so I'm not sure that a different manager is going to make the difference there.
Looking forward it would be interesting to see this tactic with Amrabat and Mount in place of Eriksen and McTominay. It worked against Brighton but they don't have world beaters on the flanks. Using this against Bayern with their world class fullbacks would probably look like a track meet, but I don't know what other options there are.