The Book Switch Theory

[Koen G]

As for the Modern Forgery Theory, I don't happen to buy into all of its elements, but calling it a fringe theory comes across, again, as a weak attempt at dismissal. It still has considerable evidence in its favor.  At this point, it iis really a question of which collection of evidence is stronger -- that supporting the MFT or that supporting a genuine 15th century origin along with its standard provenance story.

This simply isn't true, and it's what makes these discussions so difficult. There is a scientific consensus, and then there are competing theories. But those do not stand on the same footing.

Challenge the consensus. Point at its cracks and hammer away. That's how we will make progress. But the fact that we can and should challenge everything we think worth challenging, doesn't mean that our ideas are automatically on par with the consensus. 

To get back to the diagram: as it stands now, it represents a minority view, since there aren't many people who would call the Tepenec signature uncertain.