They wouldn't be deposed unless they were germane to the suit and if they were germane they would have been named as defendants.

I am curious, though, as to what he is claiming as damage. Misdiagnosis or even mistreatment alone are not grounds for a malpractice suit. There has to be some sort of negligence that causes injury or unneeded surgery as a result for a claim to be valid. Filing a claim is easy. Showing actual injury as a result is not. The fact that he was able to get a job in the CFL would show that he has no lingering issue as a result of a misdiagnosis, therefore no standing. There would have to be something else.