... than the Cardinals, three teams have already changed their starting quarterback based on performance (Philadelphia, Oakland and Buffalo). 

Two others have had different quarterbacks due to injuries and suspensions (Pittsburgh and Detroit) and one actually probably would've made a change if the backup hadn't gotten hurt (Jacksonville). 

And now the Cardinals have come in and crashed the party. 

In many of those cases, though, things have worked out performance wise, even if the teams haven't won all their games. 

Let me tell you briefly why I think this is the right thing for Arizona...

Bleacher Report - NFL