So, I'll just go with weasel wording now.....
They brought in a new GM because the last one traded up in the draft for a crappy QB. The new one drafts a new QB. You pretend the events are unrelated. If Sanchez didn't suck, you wouldn't have a new GM or QB.
No, he was fired b/c we had no depth and were in trouble w/ the cap(though it was easily cleaned up). Mark having one bad year didn't get him fired. mark helping us reach 2 title games did get him a huge raise and extension a couple of years earlier though.