You don't need an MRI to determine an ACL. The lack of stability in the knee is obvious. They use the Lachman test, the pivot shift test, and the anterior drawer test. The MRI determines the amount of damage. So if the knee is stable, they would use the valgus stress test to check the MCL. I guarantee you the Pat's doctors already knew what it was by the time Will made it to the locker room, but they do not know the extent. That is the MRI. With that said, I think the person you are responding to is full of crap.