If I predict that some data will be linear, then I am making a much stronger claim than if I predicted that the data will be cubic. This is because the chance of being proven wrong if I really am wrong is much higher in the former case than in the latter. In other words, a theory that predicts everything doesn't say anything. There is no inherent reason why we should reject this alternative over the linear alternative. Both make strong claims about the form of the data.
Evolution seems to have quite a few degrees of freedom.
So it seems to me that there are plenty of degrees of freedom here. Well, evolution can accomodate this. It just means that we got the original transition path wrong. So here we have a gradual morphological transition path from F to P which accomodates the new data. Of course, PC suffers from this same flaw.