Fantasy Upside
Marcus Mariota is going to be the Titans' starting quarterback this season. He's got a good arm and is a good enough athlete to run the ball, so he's going to have some success.
Fantasy Downside
Rookies, in general, aren't strong fantasy plays at the QB position. And considering the Titans don't have a wealth of offensive talent, Mariota will have his struggles.
Bottom line
Given Tennessee's lack of playmakers overall, don't expect Mariota to take the league by storm. The one plus is that his backup, Zach Mettenberger also is a young guy, so it's not like the team is going to be tempted to go to the wily veteran to try to win some games. The Titans and Mariota are going to take their lumps together this season. He's unlikely to be much of a fantasy factor.