Yeah, I agree with you. The club does seem to do these things properly. The logical conclusion of that thinking is that we'd never sign anyone who'd ever been injured.
EDIT (after 30 second Google search): It was a "historical" injury; Quote from Argus "Then the results of the medical revealed an historical knee issue which represented too much of a risk." http://www.theargus.co.uk/news/15417405.Talking_Point__Albion_had_to_say_no_to_Neto/
It's been reported that he's a month away from returning which, I guess, means the injury is effectively healed and he can run, etc but that he's not ready for competitive football - kicking, twisting, etc. I doubt we'd organise a medical unless we could discount known conditions. It was unknown...