If you really expected Fox to do anything in 3 seasons, then you're either a troll or an idiot, or both.
The Bears were rebuilding virtually from ground zero. This was a team not only almost completely barren of youth and talent, but was marred in toxicity from the previous regime.
Anyone who thought the rebuild was going to be quick and painless was fooling themselves. Not to say Fox shouldn't have been fired, but yes, he was essentially the Bears' Renteria. A guy brought in to clean out the garbage in the locker room and establish a positive culture.
It shouldn't have been this bad, and a lot of it had to do with Fox's decision to replace Gase with Loggains, who honestly just wasn't good at all. He also had horrible luck with injuries (that or his staff was awful at assisting in injury prevention).