From my view, KO has started its decline when the consumers are more health conscious. It will be further down when interest rate is raised more than 1% (one year away to me). When it comes to a forward P/E of 15 or so, then it is a buy. Hence, if you followed Buffett recently, you're not doing well with KO.
Pepsi is doing well with the bottle of water and I bet KO will follow soon.