Good article on this from Foreign Affairs: http://www.foreignaffairs.com/articles/143294/david-gordon-a...
Some quotes:
"Yanis Varoufakis, the Greek Finance Minister, for one, singled out Italy for having debt that was “unsustainable,” which served only to infuriate Italian Finance Minister Pier Carlo Padoan"
"Within a day of winning the Greek election, he (Tsipras) called the Russian ambassador and protested the EU’s statement condemning Russian-backed Ukrainian separatists for an attack on civilians in a Mariupol market"
"But even then, Greece could have survived its mistakes were it not for one other fatal decision: to move forward with its electoral platform before renegotiating its debt, increasing government spending without the requisite funds and reversing or stalling key reforms (...) All these factors positioned Greece to buckle in its negotiations. It was simply hemorrhaging far too much money far too fast to hold its position."