Update: As of 7 pm ET, the MCC patch is now available and comes in at 1437 MB in size. Thanks, Thomas W., and others!
The game launched last week but has had severe matchmaking issues for the majority of players. A patch was scheduled for yesterday but was delayed until today (11/20). Today's patch should alleviate all issues that resulted in extended matchmaking times and low matchmaking success rates. Plus there's a bunch of fixes for the different campaigns and a few UI tweaks.