I'd rather look at the real potential for improvement over the proven poor play the team got from Free last year. Sometimes, unknown is better than known bad.
Sometimes. I think there's reason to believe it is.
Collins was a first-round talent who played tackle well at an SEC school. The only real question about him is his ability to make the switch to the right side because of the change needed in his footwork. We don't know how long it will take him to make that adjustment, but his value as a player is higher than Free's ever was. It's a relief to know that Dallas is having him spend all of his time adjusting to the position to get to the point where he's not thinking about technique. There may be some bumps in the adjustment, but it's realistic to expect him to eventually play at a higher level than Free, if he doesn't do it right off the bat.
Green also was drafted earlier than Free because of the ability he showed at another SEC school when he could stay on the field. If he had not had the injury troubles, then he would have been drafted higher. The obvious question with him is can he ever stay healthy.
Free was drafted in the fourth round because of the athleticism he displayed at tackle at a non-power school, which had earned him the nickname "Doug Freak." However, he was clearly a project as he didn't play with power in college and had some technique issues. He improved both of those things, but at times they would show back up like they did last year. He's always been an upgradeable player, but Dallas hasn't had an upgrade ... although Parnell was at least on par with Free.
As bad as Free was, the question is whether we have that upgrade now. I believe we have two players who could be, but I need to see it before I erase those question marks.