Why a Bavarian, and why that Bavarian in particular? Was no-one with a greater connection to Greece available? Or was he chosen specifically because he had little connection to the country?
BONUS QUESTION - when he was deposed, why was a Dane, Prince William of Schleswig-Holstein-Sonderburg-Glücksburg chosen?
There was a related question posted some time back with some interesting answers, which you may find helpful.