That's a hypothesis, but it seems unlikely since there are four other European economies facing identical problems - Spain, Italy, Portugal, and Ireland. Spain in particular was a very reasonably managed economy before the crash, running surpluses and growing. So, your hypothesis would require that you attribute the problem in each of these economies to separate causes, which is probably wrong.
This is not to say that there wasn't gross economic mismanagement on the part of the Greek government, but focusing on that distracts from the real solution.
UPDATE: I'm in complete agreement with everyone pointing out that the problems aren't identical. Perhaps the question is whether, if you were to summarize the causes Euro crisis in broad terms, you ought to mention Greece's economic mismanagement first or the overall crash of the financial markets as the more important factor. My assertion is the latter, mostly echoing Stglitz's analysis here: