orthogonal writes: "But the deletions were not done by process, but instead by the fiat of a heretofore unheard of "Front Office", an end-run around the community consensus that wikipedia presents as its public face."
Damn straight. Because the community processes were failing, and we must have some way to correct for that. Wikipedia is first an encyclopedia project, and only second a community.
So, about the clerks? You know what they do?
They open cases. And they close cases. Sometimes they nag people to vote when there are not enough people chiming in to close a case. This is more of a pain in the ass than one might think. Occasionally they will write summaries of evidence (though not always or even often) or will beat evidence and workshop pages into something resembling a proper format. The committee reads the evidence for itself, writes proposals, decides the case; the clerk position has in my experience had no effect upon the actual nature of the job.
How were the clerks chosen? People the arbcom trust and think would be good at the job, usually because they've had experience working with cases. (Yes, orthogonal, insert obligatory reference to Snowspinner^w Phil Sandifer here.) Their task is primarily in interfacing with the arbcom, not with the community; their positions exist to make our jobs easier and should not have any effect on the process as seen from the community side.
If a case goes wrong, blame the committee, not the clerks; it's our responsibility, not theirs.
(I'm sure I've written something very like this on the talk page of the Clerks page somewhere, but I won't bother to look it up and likely you won't either.)