It goes without saying that Joe Flacco is the best quarterback the Baltimore Ravens have ever had. In the words of DJ Khaled, Flacco is the Ravens’ "key to success". Flacco had never missed a start for the Ravens until last season where he tore his ACL and MCL in the Ravens win over the then St. Louis Rams. He had surgery in the days following the game and was thus out for the remainder of the season.
This injury could be career ending for running backs, but Flacco is obviously not as mobile as backs.