I don't understand why some of you believe he (Collins) could be a better tackle than Free. He just does not have the feet, he is strictly a mauler. Think Kevin Gogan: Honorable Mention All-American tackle out of Washington. Dallas tried him at RT and he failed miserably. He did not have the foot speed for pass blocking although he was quite good at run blocking. He moved to guard and eventually became a Pro Bowler for the Raiders.
Collins might be an average tackle but why play him there if he can be a great guard?