Sheffield United have shit for talent but are an incredibly cohesive team who play a unique system that gives top teams fits. Overlapping CB's, lolol.
They are a quintessentially English minnow menace. Burnley and Bournemouth are archetypal examples. No other league in the world has these type of teams to such a degree. Closest would be La Liga (Eibar, Alavés, Getafe, and so far this year, Granada, etc.) and to a lesser extent, the Bundesliga.