The red flags were he was 53 y/o and never finished higher than 9th. Never won a cup or played in Europe. And was inflexible complex system, which is outdated that is only seen in Argentina and Italy 4312. 4312/diamond is a good formation for a 1 off game as change of tactic, but after a while it is easy to combat and gets exposed.
The fans, want Spalletti, Rudi Garcia or Marcelino. They fed up with the cheap no pedigree coaches, always looking for the new Sacchi and Capello. Instead of going for big names, the last big name coach was Fatih Terim and that was him coming off the Uefa Cup final and doing well with Fiorentina, hence why Rui Costa joined Milan. Ancelotti was classed as a failure before Milan.
Spalletti couldn't happen, because Inter only want to pay him 6 months money instead of the year, couldn't agree terms.
Don Silvio and Uncle Festa ruined the club.
Pioli might be OK till the end of the season. He usually has an impact to start and then fades away.