Concerning Vollmer, for the last 2 maybe 3 years he has had more severe back problems than Saffold. I don't know the extent and have trouble spelling vertebrae. I always get squeemish when we start considering players with back problems. There are a ton of examples how that often doesn't work for OLinemen. That's why Snisher have the experience, protocol procedures and get paid the big bucks to distinguish who is worth/not worth the risk. Even then it doesn't always work. Ask MM.
I just don't think one can discount back problems or assess them very easily. As an example, I have a brother-in-law on his 11th back surgery. Unless I personally experience the same injury/illness, I have no friggin idea how it may turn out.