The s3s team seems to be using a new pattern for the battle JSON files starting on version 0.3.2 (this SplatStats release should allow it to mix both patterns in the same folder but still needs to be tested a bit more). If still running s3s 0.3.1, no update is needed.
s3s' update: https://github.com/frozenpandaman/s3s/commit/38e93c2e945f12e7cc9feb0c8cf03cecc4ae6ca1