How can you be up a man half the game and not dominate?

It's a big field, I imagine you could just basically run a formation that calls for 2 guys up front but just have one

You be Greece playing a very well-organized Costa Rica.

Greece has no offense. They had Samaras basically carrying the team on offense. I really don't understand what they were trying to do tactically. It's like they go into games with no plan and just try to wing it. By far the worst team to reach round of 16.