I suppose it depends on whether the discussion is about the trial, and trial evidence (like the CV of qualified court experts), or whether the discussion is about the people that are merely doing their jobs. For example, in the trial of Casey Anthony, the neighbor's (shovel) personal history is not relevant, nor is the prosecutor's CV. If there is an expert, his or her CV is entered into trial testimony and part of the trial discussion.
Do you think that the personal details of the prosecutors in the Anthony trial should be open for discussion and criticism?
If he does his job as badly as Mignini, then yes, by all means! I don't think a prosecutor's children or home phone number should be exposed, but I see nothing wrong with looking at issues like conviction rates, the types of convictions he has obtained, charges of and convictions for misconduct, training as an investigator--in short, anything that reflects on his job performance.
I especially think that's fair game when posters such as yourself anoint prosecutors as experts by quoting them as authorities to support your arguments.