Hey Dude,
I've been playing MANUAL since Fifa 12. It appears that when the match starts both players are on MANUAL as it now takes forever to find a game on Seasons Online Manual. But as someone pointed out, there could be an option to change the controller settings when game is paused. I have not checked this myself, but I wouldn't be surprised.
The only recommendation I have is playing COOP Seasons. Even against assisted players you have more of a chance with manual because neither player can control the AI. So, no switching to DMF and using the Teammate contain or double contain for the entire match. Both players on the team have to defend. Also the Gameplay is set to AUTHENTIC which makes the Gameplay SLOWER and gives MANUAL players more of a chance.
Another online option for manual is playing CLUBS. Even though it's against assisted players you still have some sort of fun in drop ins only. Wouldn't recommend playing League Clubs as the assisted teams are sweaty and think they are good players. LOL.