I don't disagree with you. But they have stood by that, even into the season. Miami Herald article, from 21 Sept 06:
The Dolphins studied their medical reports on Daunte Culpepper and Drew Brees during their mid-March hunt for a franchise quarterback and came away with the belief that acquiring either offered risk and reward, but Culpepper was the safer pick.
...
''Let me just say this,'' Dolphins coach Nick Saban said Wednesday in addressing the subject directly for the first time, ``It was a medical decision. I don't think medicine, personnel or any of that is an exact science.
``I think we have good, professional people in that area. I think they made the best judgment they could make at the time relative to the circumstances. No one could predict the future. It is what it is right now.''
...
http://www.miami.com/mld/miamiherald/sports/football/15569267.htm