big teams mode was added after the patch (amongst other stuff).
its intended for players who do not suffer from lag or wish to play UP TO a max of 8 vs 8 real life players.
Standard mode is mainly for players who do suffer of lag and with less players there generally is less lag,
due to lower loads on the host.
Either way if there are no human players present, bots will fill in their spots.
Hope this was the info you were looking for :foodndrink: game on!