I don't disagree with your thesis that having a starting-caliber backup QB just isn't going to happen. But that's not what the Cowboys would have hypothetically needed. All they would have needed is a backup QB that could tread water until Romo could return. Weeden is not that. Cassell may not be either, but he does have
some track record as a competent quarterback on a team not that dissimilar to the current Cowboys - at least as far as their circumstances go. Once Dez returns, I fully expect Cassell to at least resemble an NFL QB.
With that said, I think his numbers in KC and Minnesota require a little bit of context. Those Chiefs/Vikings teams during that time frame were fucking awful, so aren't we looking at a bit of a chicken/egg thing here? Cherry-picking his stats during his stints for the worst teams he has played on isn't terribly instructive. It just shows he played on some shitty teams and, at worst, he merely contributed to their awfulness. When Dwayne Bowe is the best receiving threat you've got, you're well and truly fucked. Not that Terrance Williams is any great shakes but the Cowboys at least have Witten and a viable running game.
No, I don't think Cassell will make us forget about Romo, either. But he at least presents a downfield threat which should open up the running game. Defenses will no longer be able to hover seven yards from the line of scrimmage and still keep everything in front of them. Checkdown passes will go back to being a safety valve, not the primary mode of moving the football.
Speaking of the running game, there appear to be
more changes coming:
Both local papers have confirmed that Collins will, indeed, be starting at left guard but only the Dallas Morning News has anything
regarding Michael.