Chelsea has DoF, who has more say in transfer than the first team coach. It's clear Mourinho wanted Shaw, but Chelsea collectively couldn't meet the fee, wage demand & the board brought in Baba, & that Kennedy guy. Bertrand for F.Luiz at that time is no brainer. F.Luiz couldn't adapt & with Hazard playing solely on left wing, it's hard to utilized F.Luiz while maintain the defensive stability of the left wing with Hazard doesn't offer defensive cover for any left back. He happened to be the best player in the league. Would you ask your best attacker to play to his weakness or to his strength?
Again, the board has more say in the transfer than head coach. We don't know the full story. Mata was surplus to the requirement, not a bad player. Same with Lukaku & KDB. Lukaku only really stepped up into another level this season. KDB is still not on Hazard level. Building a team is not throwing big name together. KDB & Hazard till this day failed to make a good team together. Would you stick 2 together even if it means the collective combination of them is worse than Hazard at his best + Pedro or Willian. Don't forget Chelsea won the PL with Mourinho doing all of this.
Bonucci took quite a while at Juventus to establish himself to the height he's now. Again Samuel Chivu Materazzi Lucio won the Treble with him & Inter. Ask any Inter fan, they would trade any single player for a Treble. Would Bonucci at Inter until now would be enough to them the Treble? He yet to do it with Juventus, mind.
Your point is full of hindsight. You look forward future but you also have to watch your position & your next step. SAF didn't get his job to go with a young team from the get go. He built the culture, winning mentality, the stability for the first team by winning. Fortunately with some talent from the academy, he integrated them & made the team. Imagine instead of having Co92 he had to deal solely with Fraizer Campbell, Cleverley, Welbeck, Shawcross, Chris Eagles... history would be very different. Then talent is one thing, applying your talent is another thing. Anyone who use reason instead of bias/ agenda can see that Martial has been dropping in performance at least since the end of last season. It didn't even start with Mourinho. Shaw had a terrible injury. Logically, it's hard for him to get to the level he was pre injury. I don't see anything wrong with Rashford situation. No other teams would start an U20 over Zlatan who is not bad (top scorer for us). Again, it's another case that you rather be mid table team & wishful thinking that in the end your youngster would be all world beater to & repay you more than you have to suffer; even if it means you refuse the chance to win something you can possible achieve at the moment... It's borderline fantasy, while football is realistic matter.
What did Poch win? Who bought Alli, Eriksen, Dier...?
Where is De Boer now? Is Ajax & their fan really happy with him (I didn't hear just positive thing)?
Atletico bought well & they have DoF. Simeone did respectively well. You have some great young players doing well while you forgot that they also couldn't develop other young players, Vietto O.Torres, Siquera... even Gimerez has been benched for Savic (former City player) for a while now. Diego Costa was sent on loan all over the places before he really broke through.
Joe Cole SWP were more a case of British overhype, which is never. Defoe arguably as talent as Joe Cole & also having flaw. Defoe never got recognized since he's at big clubs, so it's him he underachieve but when it comes to Joe Cole it's because the coach he underachieve. You have the media hyped Walcott Lennon as better than SWP when the first appeared on the scene too. They still underachieved. Mourinho is to blame too?