Sorry, newbie's post limit.
Dead cat bounce is a reality, even for a club of your size. The atmosphere in José's last months was so toxic, that anyone who came right after him, would've been a bit of fresh air for the players and the fans. You're a massive club that appointed permanently a manager who would've never gotten the job if it wasn't for his past connection(s) to the club. After all these "wrong" appointments since SAF left and the lack of long-term vision, it always looked like as a gamble which reeked of a panic decision. Of course hindsight is a wonderful thing and the board was stuck between a rock and hard place, but it should have held back and waited until the season's over. Then assess the situation and I'm fairly certain that OGS wouldn't have been hired permanently.
He's a legend as former player and will always be, no matter how his stint at your club will turn out to be. He's not the first and certainly not the last in this case. However the rebuild can and should go without him. It's a vision, a project and not tied to the manager himself. From an outsider point of view, he's not really looking up to it and it's quite incredible that some here celebrate a win against Norwich or Partizan as a credential to his project. I understand the rebuild necessity, you're in need of it and it will take you a couple of years before you'll be challenging for the title. Still, you're better than 10th, even with your actual squad. You need a proven builder and I don't think OGS is one of them.