I don't like the situation for CJ3 at this point. Over the past few years, it has been near impossible to predict which Titans RB will get the carries from week-to-week. They now have three young RBs, and CJ does not look to be the guy that will get the premium touches near the goal line, and due to the youth of the guys they have, it's unlikely that the situation will change over the next 2-3 years.
Kevin Smith will be the starter from day one in an offense that is going to focus on running the ball. I know it's Detroit, and that's a risk, but at least then there is some predictability from week-to-week so you can make lineup decisions.