My take.
You're a QB, a starter, because you're great in practice. It's game day and you're not doing too well. Maybe, just maybe if I pull you out and put in your backup he'll show me something I don't see Mon-Friday. Maybe not. Maybe he'll suck, just like in practice, but the only way for us to know if he sucks is to put him in.
What you don't do is play Vandeberg ever snap in 2012. Even if the backups are all in a wheel chairs you send a message to the rest of the team that sucking has consequences, and that means you get pulled for a series, or a game or a season.
Now if you wanna blame Greg Davis ... fine ... THEN FIRE HIS ASS AT SEASON'S END. But that didn't happen did it.
The point is simple. Davis was a place-holder, which is a moral failing in itself. And Vandeberg wasn't pulled because someone MIGHT look better than him, and we can't have "controversy".
This is where you reply with, "Champ you want answers?"
And I loudly reply, "I want the TRUTH!!"
And you come back with, "YOU CAN'T HANDLE THE TRUTH!!!"