I don't have a lot of hope for Anderson either, but I'm willing to wait it out and hope for the best. If Anderson sucks, then what benefit would Leftwich give us if he's practically a black Derek Anderson with more leadership but a slower release?
Basically, as much as I don't trust Anderson, I wouldn't trust any of the other guys mentioned even more, and would rather just get our rookies some playing time.
I guess it depends on what kind of offense we roll out with when it matters. You can plug in a serviceable backup and still do well with a team like the Titans where you simply need to manage the game, but I think the reason we're going with Anderson is because we expect to make things happen through the air.
We can throw out names like Rosenfels, Troy Smith, Thigpen, and Dennis Dixon, but despite being 'veterans', they still don't have a ton of play time in the NFL. I would favor both Hall and Skelton over any of those guys simply because they've had a full off-season to work with our players and our playbook.