1. Can't sack Jimmy as we can't afford it
2. No-one of the fav's mentioned would want the job - think about it - Willie & Wiggy "Eric, come manage Aberdeen" Eric - "Will I get some cash for new players?" Wiggy and Milne - "Er, we have to pay the 2 Jimmy's off, so you could sell to buy" (sound of phone hanging up)
3. We all know if we sack Jimmy we have to go cheap for a replacement - so it would be Nicholl if he didn't walk or worse Sandy Clarke - They are the only two financially viable options if we sack JC. As an outside gamble we might end up with Leighton.
As has been said, JC has been fairly successful as a manager at Aberdeen, just hasn't got the boards backing and has signed second rate players who are now not performing.