What went wrong? The answer, I think, is twofold.
First, Rowan Williams, in becoming Archbishop of Canterbury, reached his level of incompetence. He became yet another illustration of the Peter Principle. He was a fine writer and theologian, one who seemed to work well with others. When he became Archbishop of Canterbury, however, it became clear that what he was not was a competent politician, and that’s what he needed to be, what Archbishops of Canterbury have often needed to be. (Some spectacular failures in this regard come immediately to mind.)
His abandonment of his friend Jeffrey John proved a fatal mistake from which Rowan has never recovered. He no doubt thought—I offer the most generous analysis here—that sacrificing John would buy him goodwill among Evangelicals. As any seasoned politician might have told him, however, he was merely throwing bloody meat to the sharks. He proved that he could be intimidated, and those who should have been considered his theological enemies were quick to learn the lesson of the demonstration.
Second, Rowan came to the bizarre conclusion that he should put aside his own personal beliefs—perhaps even his own personality—in order to play the role of Archbishop of Canterbury as he understood it. It is this completely unexpected decision that has so confounded many of the people who recommended him for his current post. After all, Rowan was selected as Archbishop of Canterbury for his accomplishments, his personality, and, presumably, for his personal beliefs.
One can hardly fault the Archbishop of Canterbury for trying to keep the Anglican Communion from disintegrating; doing so is surely a task entailed by his job description. In abandoning his own beliefs, however, he has allowed others to frame the rationale for Communion unity—the establishment of a reactionary worldwide church distinctively un-Anglican in its ethos—and his rudimentary political skills have managed to alienate Anglicans of every persuasion, save for the dyed-in-the-wool institutionalists.
Rowan Williams does not want to see the Anglican Communion self-destruct during his incumbency. I fear the only way to guarantee that outcome, however, is for him to step down. Although this would likely bring an Evangelical to the See of Canterbury, it is difficult to see how anyone could do a worse job than the incumbent. Rowan is playing the role of Archbishop of Canterbury as best as he can according to his understanding of that role. Alas, he has proven to be a very bad actor.