Offensively, the Tennessee Titans haven't been dynamic in 2013.Tennessee is just 29th in the NFL in total offense and has averaged just 21.3 points per game. And, going into Sunday's matchup against the 49ers at LP Field in Nashville, there's a question of who will start at quarterback, backup Ryan Fitzpatrick, or Jake Locker, who returned to practice this week from injury.So, on paper, the Titans (3-3) don't appear much of a threat to the San Francisco defense, which has been playing very well in three straight victories over the Rams, Texans and Cardinals. Yet the 49ers (4-2) go into the game knowing that starting nose tackle Glenn Dorsey may not be able to play because of a hamstring injury sustained in last week's victory over Arizona. Plus, left defensive end Ray McDonald is dealing with a partially torn biceps and right defensive end Justin Smith is working through a shoulder injury. Dorsey, McDonald and Smith all missed practice time this week.That's not a good situation going into a game against one of the most explosive running backs in the league, Chris Johnson.The last time the 49ers faced Tennessee, in 2009, Johnson rushed for 135 yards and two touchdowns. For his...