Outside of maybe one or two posters, I don't really see all the Petey hate? Generally I see reasonable discussion regarding the nuances of Petey's injury, recovery and poor play. It would be better for the general quality of discourse on here if we can just focus on the merits of the reasonable views put forth, rather than overgeneralize, sensationalize and strawman the opposing side's views. If it frustrates you to discuss or debate the minutiae of this topic, for whatever reason, then just don't partake in the discussion or debate.
I honestly find the whole thing to be quite disheartening.
I am not a medical practitioner either, but I did and probably still have patellar tendinitis, and the tendon was shown to be inflamed on a MRI of my knee. So, presumably - and I say this with zero qualification or expertise - an MRI is relatively conclusive since it should should whether the tendon is inflamed or not.