A new fundamental change in Call of Duty: Black Ops 4’s standard game mode set is the number of total players. The player total in standard matches is now 10, with 5v5 action in game. Previous Call of Duty titles had 6v6 standard (or 9v9 in Ground War).
Treyarch says this change was made to better suit the core mechanics and changes of Call of Duty: Black Ops 4. The maps set in Call of Duty: Black Ops 4 is also medium to small size set to cater to this playstyle in game.