BUZZARDS BAY, Mass. — The rhetoric surrounding David Petraeus’ fall from grace has been nothing short of epic. The tawdry affair of the general and the biographer has assumed the proportions of a Shakespearean tragedy, complete with a tragically flawed hero and an evil temptress. The media has been gushing, even fawning, in its description of Petraeus’ accomplishments, and his disgrace is being portrayed as a national disaster. The reality is much more mundane.