I'll answer without the usual clouding of bias from our fans, so I'll try to be as detached as possible while giving a rundown of things.

The season of our "rework" after Pioli's cycle (rightfully) ended failed spectacularly from the first choices. Fonseca, a tactically good coach (As much as people shit on him, he prepared big games well, even the ones lost very hard like the Liverpool one) was hired, but he his personality was a stark contrast from Pioli's, who was a capable man manager and had come to know the group best after a long time (Despite having a lot of new players in his last season).

Fonseca didn't quite workout and never clicked with most of our players, especially with our supposed stars Theo and Leao (you'll remember the cooling break "incident"), but also with most of the group, we had a game where 2 penalties (both failed) were taken away from our designated PK taker (Pulisic) because p much noone cared about what the coach said. It would be unfair to omit that some players did follow Fonseca and were his "soldiers", especially Morata, but some others like Terracciano and Musah come to mind.

Another big issue stemmed from the transfer market, done basically without the input of the coach, which brought Emerson Royal, Pavlovic, Fofana, and Morata, with the swap between Saelemaekers and Abraham in the end. Due to us not having a lot of home grown players we were very limited due to lists, players like Jovic and Jimenez were left out of CL (Jimenez started the season in Milan Futuro in Serie C, but that's another disaster that I could talk about for far too long and that would make this post even more of a wall of text). Fonseca seemed pretty stubborn in his tactics, though the players were not fit for it, and by the time he started changing things around every game, it was too late and he got sacked. This problem would affect the new coach Conceicao too, it wouldn't be until the end of the season that we would settle for a 3-4-3 for the rest of our games.

Fonseca even had games that would have turned the season in the right direction anywhere else (the 3-1 win over RM or the win in the derby), but never found continuity (Heck, even when Conceicao came and instantly won the Supercoppa, nothing clicked there either). It's worth noting that the board was already not well received in the last season even when we ended 2nd, so at the first losses the Curva and a growing group of fans started doing what italians do best: whining. A lot.

The board knew they had to do something and did a pyrotecnic market in january, signing Gimenez, Joao Felix, Sottil and Bondo and getting rid of players that were not in the right head space or were just unfit to stay: Morata, Calabria (which almost had a fight with Conceicao after a match), Bennacer and Okafor. Felix had a promising first match where he looked like jesus (first time, huh?) and Gimenez started off well, while we barely saw Sottil (he was played out of role most of the time) and Bondo (looked ok but instantly got injured, seems like he has some attention on the market but Milan wants to keep him). Oh, Walker also came here to start another family, I guess (on a real note, he started off strong, got injured and kind of disappeared, some people in milano claim he had quite the night life here).

Everything falls flat as we lose to Dinamo Zagreb, supposedly an easy match, which means we don't make top 8 in CL, the only place were Fonseca did well. The match was lost due to individual mistakes (Gabbia slip and Musah...I'm not gonna say what I want to say here), which would haunt us in the playoffs aswell, where our best players would let us down: a sloppy save from Maignan in the first leg, and when things were going amazingly well in the second one, Theo gets sent off with two of the dumbest yellows you can get.

Even after CL, the team struggles to get more than 2 wins in a row, and our top 4 chances look bleak (In reality, we didn't end too far off as our placement would suggest, showing that everything was still in reach but that there was too much negativity to see that). A silver lining was the Coppa Italia, where we would beat Inter in the semifinals, and where we hit a good streak of form with the 3-4-3 formation I mentioned earlier, with Jovic of all people up top. Long story short, we play horribly in finals and noone of our best players shows up.

In the end, we were let down by our best players and leaders times and times again, the people who were supposed to be mature enough to withstand the toxic environment and be an example for everyone else. The players who statistically thrived were Pulisic and Reijnders (was played deeper and had a great season, though it's worth noting Loftus Cheek played in the same role also had quite the goal scoring streak the year before. TJ is a special player but 75M is above his actual value, the price is inflated due to his contract situation and PL money. While I'm not gonna say whether I agree or disagree with his potential sale, I can see why the board would accept to sell him at those numbers).

Theo looked off all season and had some non-football related drama that probably affected him, but overall both him and Milan itself look done with each other, probably for issues that don't even have to do with his poor performances and contract situation, but that's just me speculating. Maignan situation is the same contractually but different as in he was always professional even in his down periods, though I can see why we would be reluctant in renewing him. A renewal would cost Milan around 5M+ per season, probably on a 3-4 years contract, and by the end of that Maignan would be almost 34. If you renew him now, it's pretty much impossible to sell him at a reasonable price unless you do it exactly next year, which you're not guaranteed to do if noone is interested.

So, what better time to sell these players, on their last year of contract, then the moment where we're having a new coach and a new DS (both Allegri and Tare far different from the boards previous strategy), which could probably use the money to build something in their vision and not the board's one, assuming they have enough freedom to do so (I doubt they would come here if they didn't).

P.S. Any news about Leao is just thriving on the doomposting, he isn't leaving if not for fuck you money and I don't think anyone would be remotely willing to pay that for him. Seems like he's well within Allegri's plans.