What criteria is used for matchmaking

I was just wondering how they go about matchmaking in Warzone? What stats do they use? Is it K\D or SR#? I know for the ranked games its obvious, but most of the WZ games are way mismatched, even since they added the new options in for search preference. If fact it almost seems worse than it was. I noticed I haven’t gotten any disconnects yet, which is good. The JIP games have increased 2 fold. It’s annoying getting dropped into almost every game that’s already a lost the match.