Well, I don't know anything about Rhett Reilly or Jake Jensen, but if we get down to them, we'll have a mountain of issues to worry about.
None of the QBs on our roster has done nearly enough to make comments like "I believe [insert name here] is clearly our best option this season" anything more than conjecture.
"Concussion-prone" is a dated way of looking at it. One or two bad ones can have lasting effects. And each concussion does make the next one more likely. Maybe it was a blessing in disguise that he didn't play last season so that his brain could fully recover, but full confidence that it won't happen again is completely unwarranted.