There is irresistible evidence right now that signing coaching talent from Spain's northern coast brings guaranteed success, and Arsenal, Liverpool, Aston Villa and Chelsea need no convincing.
In international terms, the European and world champions (Spain) are coached by a Basque (Luis De La Fuente), in club terms, double Champions League winners PSG dance to the tune of another north-coast Spaniard, Luis Enrique, and the reigning Europa League holders and English champions owe their success to a couple of guys, Unai Emery and Mikel Arteta, who grew up within a few miles of one another in San Sebastián (part of the Gipuzkoa territory in Spain's Basque country).
It is, literally, a phenomenon. This is a coaching domination by a small community on a grand scale.