Vince Young was only taken out of the line lineup because he was injured. After he was healed up (all of that "head case" stuff was pretty much BS) Collins was kept in becasue he was WINNING games which was unexpected. Why push a two year played into the fire when it is not going to hurt to have him sit on the sidelines and learn? Not to mention something that most don't think of - if he doesn't play a lot his body may last a few more years later on.