Just as this piece was being published, news broke that Tennessee Titans rookie quarterback Marcus Mariota had suffered a sprained knee in Sunday's loss to New England, and he will miss the last two games of the season. The injury is not severe, but with Tennessee well out of the playoff race, there is no reason to risk the long-term health of their franchise passer. Mariota, completing 62 percent of his passes with 19 touchdowns and 10 interceptions, has enjoyed a fine rookie season aside from two significant weaknesses: health (he missed two games earlier this year, also with a knee sprain) and ball security (he leads the NFL with ten fumbles despite missing nearly three full games).