I personally have felt that the whole "clubhouse demoralized because of Hader" thing was the very low-hanging fruit of things to blame for this season. The team just isn't THAT good. It's decent, but not in the echelon it was in 2018, or even 2019 or 2021. Their schedule turned much harder later in the season.
That said, I'll still think they'll get one of the Wild Cards.
Sidenote, I'm also tired of the idea that they should have traded him at last year's deadline. They were a 95-win team that got cold at an inopportune time. Last year was absolutely not the time to trade him, they had a chance to do something last year. And it's baseball, they still do now. But I think they traded him at precisely the correct time, even if he was gangbusters in SD right now.