Now which one would you sign?
None of them - it is not my business to decide this. My personal opinion is, that he neither does a very good job, nor a very bad job. He is just averaging it all out into a plushy unidentified nothingness.
I think he is sure replaceable and Mike Griffin is sure the last person, who has to fear being unemployed for long. But the question is: Why do that at all?
I think all Mike Griffin needs, is some fire below his injector plate. Let's see how he performs under pressure. Does he excel like the few great administrators of NASA, or does he break? If he can't deal with increasing pressure, can't ride on top of the wave - fire him, for his own good. But if he suddenly shows more than some promise of talents, real talent in such situations, don't be a fool. Such managers have to be kept.