Mark,
I do understand that for each F level (F1, F2, F3), the predicted probabilities sum up to 1.0.
I also understand that when I trace each line (say, the inverted V shape) across each F level, I am given the probability for that y-object (say Shade 31) at the F setting that I choose.
What I am questioning is why, for example, the inverted V shape of Shade 31 when the predicted probabilities are .132, .055, .113 respectively at F1, F2, F3? The shape must mean something. It certainly does not appear to correlate with the location (top, middle, bottom of the graph) of higher probability regions that you point out.