Admittedly, the scenario I present here has no more substantiality than the daily accusations emanating from the White House against any of its critics that fills the media, but the pattern of behind-the-scenes operations we have witnessed so far suggests a hint of validity.
Let us suppose that the whole Mueller affair was contrived from the beginning to get Trump off the hook. From all media sources, we heard how incorrigibly honest Mueller was. Trump and his associates made much noise as to how the whole business was a "trumped-up" conspiracy by his opponents, and he exercised no restraint in condemning the whole process and discrediting the integrity of all involved and the conclusions to be reached. There were constant hints that Mueller was about to be fired.
But, behind the scenes all the critical players involved were actually participating in a scheme to clear Trump in the public view and boost his popularity. So, when the report from the incorrigible Mueller comes out essentially acquitting Trump and his entourage, albeit with some negligible lapses, the verdict would be much more convincing than if a more controversial person had led the investigation.
My apologies to the real Mueller for this fictional dramatic interpretation.