The problems started long before Rangnick came in. The squad was already poorly put together by previous managers, who recruited quick fixes (that didn't work) it doesn't matter how good technically you are etc etc you have to have the right character a willingness to run and be selfless. There are so many issues he's been left to pick up and deal with Lingard, Pogba, a non existent midfield, awful fullbacks, defenders.
Some of Rangnick's selections have been interesting to say the least, even from the outside you'd struggle to pick a decent starting 11 each game. Look at the squad vs Arsenal how many would you keep? Starting XI maybe 7 from the subs you prob keep 1 or 2.
The board and owners are to blame for ridiculous contracts which have made it hard to move players on.
I'm sure Rangnick is consulting whilst being manager, no better place than being hands on to fInd out the real cause of why these players have given up. I hope he stays and supports ETH and that ETH is given full control of who stays and comes in. I hope he and the players can demonstrate an identifiable style of play something we have not had for years probably since LVG (albeit a boring slow style)