The fact that the Indianapolis Colts are currently an 0-5 football team without Peyton Manning proves the importance of elite quarterbacks, not just the importance of Peyton Manning.

The Indianapolis Colts are a trainwreck without Peyton Manning.  They currently have the worst record in the NFL.  The Colts are 0-5 while the Dolphins and Rams are both 0-4.

The loss of Peyton Manning shows the importance of elite quarterbacks.  An elite quarterback makes the biggest impact on a football team.  There are teams that can survive losing an elite non-quarterback to the point where they won't be winless five games into a season solely based on that loss.  However, losing an elite quarterback puts a franchise in a likely position to struggle immensely.  Ask the Colts if they agree or not.