The Rams must've seen enough in his 16 starts in 2016 to bring him back for another two years as that's how long they've re-upped him for:
Rams are bringing back C Tim Barnes on a 2-year deal.— Sam Farmer (@LATimesfarmer) March 9, 2016
That doesn't mean they're done at center. There are other options in free agency even with headliner Alex Mack off the market to the Atlanta Falcons. And perhaps more likely is the 2016 NFL Draft offering one of the deeper center classes in recent memory.
For now though, it's a familiar face at center with experience dealing with both Case Keenum, who was given a top-tier tender from the Rams earlier, and Nick Foles.