The affliction was carefully chosen because there is no 'scan' that definitively shows the issue. It is diagnosed by past health, symptoms (such as where the pain is and what time of day your foot hurts most), and how physically active a person is..In short, "You say your foot hurts"
It is treated with rest. Based on Byrd saying that he played through all of last season with it, his issue would be considered critical at this juncture and Byrd should be getting steroid shots or having surgery to correct the problem.
So either his doctors are incompetent way beyond the level of malpractice that he has one of the longest diagnosed cases of Plantar Fasciitis and they have not adjusted their treatment recommendation or there is more
Keeping in mind, he has consulted outside doctors who may not be discussing particulars with the team. Does anyone know the exact legalities that an outside doctor has to share information with the team.
I definitely give Parker a huge amount of credit for finding a nice loophole.