Mental. With the money available these days, why don't these lower to mid tier clubs scour the globe for the best coaching talent, identify and pick the likes of Simeone, Pocchettino while they are still in their late 30s, just stepping into coaching. It only has to be done once properly, then you're set for years (as long as you're as a sensibly run club who don't press eject after 5 bad results in a row etc)