Aquiring David Carr does not mean abandoning Tarvaris Jackson.
If the Vikings sign somebody like Jeff Garcia, it is time and the way of all flesh which requires we would have him for 1-2 years. It will be accepted, practically required, that Jackson then will take over the reigns. Hopefully he'd be ready.
If the Vikings sign somebody like David Carr, it is the Vikings' choice to have him for 1-2 years. If he is average, then they can have him for a short time and turn it over the Tarvaris Jackson. If he is good...well, then they never have to turn it over to Jackson.
When you have a QB with "potential," you don't know whether he's actually going to be a good quarterback. At best, it's a 50-50 proposition. At best. If the Vikings get a 1-2 year solution with the intention of starting Tarvaris Jackson around 2008, what do they do if Jackson turns out to be no good? Then the Vikings get to suck.
But what if they had options? Who says you can't have 2-3 good young QBs on your roster, and find out which one can turn into a franchise QB? If the Vikes have two guys who could become the QB for the next 10 years, well, then they've got twice as good a chance at finding their franchise QB than if they have one.
I do this on Madden all the time: when I draft a QB, I don't KNOW that he's going to become a star. I hope he will, and I've invested in him, but I don't know. Then, if a QB with potential opens up cheaply or in a later round, I'll get him too. If that first option doesn't work out, there's a chance the second option will. You just never know.
The idea that you are only allowed to have one QUARTERBACK OF THE FUTURE, and that if you acquire another QB under 30 you have given up on your QUARTERBACK OF THE FUTURE is ludicrous.
Tarvaris Jackson may be the Vikings' franchise QB. He may not. But there is no reason to bank on it, to set the franchise up in such a way that requires him to be the franchise QB by 2008 or 2009. It can only help to have other options, to have somebody else who might be able to take that franchise QB label. Jackson is a second round pick--he's actually cheaper than a lot of backup QBs, so there's no reason not to keep him. Carr makes a fair amount right now, but if after one year he proves worth it, great, and if he doesn't, you can either abandon him or renegotiate his contract.
It just makes too much sense to bring in David Carr. He'll be 28 in 2007. Perhaps he went through is growing pains with another team so he doesn't have to with the Vikings (if Jackson does become the guy, expect some early struggles like in 2006). He may turn out to be the Viking QB of the future. He may not. And bringing him in to play QB for the Vikes is a long, long way from Childress and company saying "we were wrong about Jackson; he'll never be the franchise QB." Either could, and if both are good, then all the better.