Every year, Forrester uses the results of its Customer Experience Index (CXi) benchmark to see which firms made big strides in the race for customer experience excellence. In our 2014 data, we saw Delta Air Lines' CXi score go up by 13 points, making it one of the big upward movers of the year. In this followup report, we reveal how the legacy airline went from the middle of the pack in its industry to a virtual tie with top-rated Southwest Airlines, and we highlight what other companies can learn from Delta's success.