"Alf"
I remember when the opposition would switch to a 3-4-3 if they were losing. It's a very basic but obvious thing to do. Not sure why KONAMI removed this........ But you can programme the opposition to switch to this attacking formation.
All you have to do, is in the Edit mode, Edit Team, select Gameplan 2, 3 or 4 (not 1), these are usually preset as "Standard", just change one of them to "All Out Attack" and select the 3-4-3 Formation.
Unfortunately you will have to adjust every team to have this option, but it's worth doing.
Try it with one team and then play against them. If you're winning by 2 goals, by the 70th minute they'll switch and start pelting you with crosses into the box. (it's great to catch them on the break though).