Official word of what specifically has been fixed is still being waited on but according to multiple Call of Duty officials on *** we know this patch was released to address all connection / network related problems and all the rank / stat problems that users have been facing since the game was first released.
We have noticed first hand though that things seem much smoother than they used to be, we played a few games without any kind of lag at all which was great! It makes the game so much better and fun to play when its smooth. Only time will tell whether the stats fix we’ve been promised will turn out to be true! I myself will continue to be cautious but hopefully it should all be good!