Staford is as brave a QB as I've seen. He took a beating and played through injuries in Detroit. He played on a hurt leg that affected his throwing last year but didn't say anything about it other than "It's fine."
He's taken a brutal beating this year and it's no wonder that he's looking at this kind of an injury as a result. I look back on all the plays that take a long time to develop, with that Swiss cheese O-line, that had me saying "No, no, NO!!!" from snap to crash when he took hits that dropped him awkwardly. I thought: What the hell is McVay thinking?
And, the outside doc may not have confirming tests, but consider: McVay is no doctor, and the team has a vested interest in putting Stafford back on the field. They'll do it for money. The outside doc stated what the treatment outcomes are, given the specific symptoms involved and where they point. I'm not going to dismiss his opinion.
