Leicester, being run by an extremely suspect group of ownership and in a free fall in the last few years, still managed to attract van Nistelrooy mid-season. A 48 yr old who ended up winning the Dutch Cup and Dutch Super Cup while finishing 2nd with PSV in his only season in charge.
Wolves, another team in the same boat, keep attracting managers like Lage, Lopetegui and Pereira who won leagues and trophies that someone like Ange can only dream of.
A perennial bottom half team like Palace managed to attract Glasner mid-season when they were hovering around the relegation zone, a former EL winner who also managed to qualify for Europe on a number of occasions.
This is the type of pull that this league has. With this in mind, trying to explain this appointment away as just another instance of Peter Principle, or Levy failing to find anybody better after exhausting all the possible options, doesn't do justice to what kind of a failure this has been.