I just implemented a stamina system. Players now regain stamina over time and expend it when used to move around the field.

Pay attention to the blue circle!

The more tired a player is, the less he will be able to support in his zone. If it is exhausted you will not be able to move it.

So use your movements wisely so as not to exhaust your players and continue to have an advantage over your rival.

I think I have to fine tune the amounts of energy. Right now moving players is not a great handicap compared to what the opponent spends.