Chris Johnson only rushed for 1,364 yards last season, and for CJ2K, that's an off year. One reason his numbers suffered was that the Titans had little in the way of passing, so Johnson regularly faced nine guys in the box. Another reason was the deterioration of the interior line. Back in 2008 when the Titans went 13-3, their offensive line was the best in the country. If the Titans want to see double-digit wins again, fixing the interior line is a must.
One place to look is free agent guard Justin Blalock. Since he happens to be a free agent at the same time as his superior teammate, Harvey Dahl, he may not get the deal he wants from the Falcons and could leave for greener pastures. With two hall-of-fame interior linemen on the coaching staff (Head Coach Mike Munchak and O-line coach Bruce Matthews), the Titans pastures are pretty green.
Another option to consider is standout undrafted free agent center Jake Kirkpatrick out of TCU. He helped anchor the Horned Frogs' line with Marcus Cannon, helped them to an undefeated season, earned All-American honors and won a Rimington Trophy along the way. As an undrafted free agent, he'd also be a cheap, but effective option.