The Orthoprax rabbi has, of course, provoked a great deal of discussion on the blogosphere - most (but not all) hostile. One of the more thoughtful responses I've seen comes from The Rebbetzin's Husband, a former pulpit rabbi now in Toronto, who says: "There are few professions which are worse for one’s belief in G-d and Judaism than the rabbinate."
• A rabbi who really engages a community lives his life under theological siege, constantly facing people’s questions and challenges against faith. It’s like water sitting on a roof; eventually, some will seep in;
• A rabbi sees all sorts of tragedy and pain, and no one comes along to reassure him as he reassures others;
• A rabbi has no time for emotional bounceback, let alone philosophical bounceback, from the pain he sees;
• A rabbi lacks the space to step back and work through his theological challenges; he gets no religious Time Out. Whether they are right or wrong, other people can and do drop out of minyan or shiur for a few days, but the rabbi has no such option;
• A rabbi normally devotes little time to read works of hashkafah that might reinforce his belief; all of his time goes into the community. Reading it in order to teach it doesn’t count!;
• A rabbi sees the weak reasons behind some people's belief;
• A rabbi sees how some people turn to Judaism not out of strength, but out of absence of anywhere else to turn;
• A rabbi sees the professed believers who act immorally and corruptly, and knows what others get away with.
Of-course, it remains completely unclear how many rabbis really do suffer from profound crises of faith - any evidence is anecdotal, and we don't even have much of that. However, if you accept The Rebbetzin's Husband's basic premise, he has left out two factors I am sure must be significant.
First, knowledge. Clearly, rabbis are highly educated Jewishly, and therefore more aware of and more exposed than others to the contradictions and holes inherent in religious texts and thought. Obviously, they are also better equipped than others to deal with and bridge them, but for some, ultimately, the doubts may prevail.
Second, they will know far more than many others about the politicisation of organised religious life - the practical / sectarian considerations which drive some "religious" decisions, the hypocrisy of some major "religious" figures, the real influence of busybodies on religious decision-makers, etc etc etc. I wouldn't be surprised if this kind of thing drove some rabbis to doubt the entire framework.