The reason barcelona won the CL only 3 times in the Messi era, explained
But seriously, Valverde is no genius and wasn't doing a great job, but he wasn't doing a bad job either. The sooner you guys accept he was handed a bunch of square pegs and round holes and he mostly found good working solutions, the easier the transition
Your team is now where we were in 2017/18, except you lack the mental flexibility and adaptability to adapt
The reason is we have a pragmatic manager that might serve to stady the ship like in his first season after Neymar left and our midfield was devoid of life, he used the 442, found working solutions like you said and did an almost pefect job with the tools he had, but the Roma game (not just that game, 1st leg vs Chelsea too where Willian could've nailed us 3 times and sent us home) showed huge flaws that a manager can't have if he wants to perform at the level Real Madrid or Barcelona need to perform.
But in two and a half years he hasn't been able to accomodate players like Griezmann, Dembele, Coutinho or Arthur in the starting 11, I wouldn't even be shocked if Xavi came tomorrow and suddenly De Jong kicked up 2 levels his performances, and he's also wasted great squad options like Semedo, Deulofeu, Alcacer, Malcom, Denis Suarez and lately Firpo and Aleña. He makes a good job working with workhorses like Lenglet, Vidal or Paulinho, and while you need that kind of players to win trophies, you need to mil the most from your creative ones, and he's failed to do it, not only that, when push comes to shove the kind of players he seems to extract the most from, like Paulinho or Vidal, don't even start in the bigger games.
We're not in your 17/18 January, your best midfielders had 2/3 more elite seasons on their legs and not a lot of potential coming through (Isco was already burned a lot of times, Asensio... at least everyone knows now what Asensio is only good at), we have a team with young blood in De Jong, Arthur, Dembele and Semedo that can easily be starters, hungy players that don't come from winning 2 UCL titles and need to earn that silverware in Lenglet, Sergi Roberto, and Griezmann. We basically have all the pieces we need to shake this team up and start trying to do bold and beautiful football, yet we're being hold down but a manager that wants no risks while keeping a core of players clearly past it in our starting 11 everytime we face a real challenge.
When you say we lack the mental flexibility you mean our players or our board?. Because I think this group could thrive under a different manager, the board are the ones holding everything down, starting with Valverde because they feared sacking him and due to their incompetence signing a worst manager, now at least they're doing something, maybe out of fear and desperation, but sometimes actions taken out of fear can lead to success, it's not like Bartomeu was on his way of doing something of value in the rest of his presidency.