Sometimes, teams will be severely outmatched. What should a coach do in this instance? It is hard to strike a difficult balance between letting the score get out of hand or embarrassing the other team. The goal in this instance is to make a somewhat competitive challenge without humiliating the other team.
To me as a player. Losing 5-0 to a 11v7 is just as humiliating as losing 22-0 to 11v11. If the other team plays keep away instead of try to score goals, that is insulting and frustrating.
The perfect theoretical solution is for the coach to handicap his own players without the other team noticing. Keep-away and removing 4 players is noticeable. Shouting "Only 2 touches" so the whole field can hear is noticeable. Obviously the perfect solution is theoretical as there will always be some sort of notice to any solution, but the closer we get to the theoretical solution, the better.
Switching player roles is not that noticeable. Telling your subs they only have 2 touches and subbing them in so the whole team is on the same page is not noticeable. Telling your team (via subs or half time) that they can only volley or header a goal from a cross is not that noticeable. Doing your best Spain vs Russia cosplay, using only the weak foot to shoot or pass. All this is really the most a coach can do. He should also tell his players to not advertise that they are being handicapped.
And for God's sake. If you put the goalie on the field, inform your team and your goalie at halftime that they shouldn't celebrate like madmen when the goalie score his first goal ever, which just so happens to be the 11th goal of the game.