I think they should leave it alone if they cant do it without increasing the cheating. Basically, the way to do it is to make two basic things happen.
1) The CPU AI must respect player stats. If it does that, it wont be able to do messi like things with average players
2) The CPU AI must respect the tactical attributes set in the formations screen. So if a teams tactics are set a certain way in the tactics screen, the CPU should play that way and not always do the same passing tactic. This is very easy, all konami need to do is configure each team to use different realistic tactics based on changing the attributes in the tactics screen which decide how a team plays
For example, configure Inter Milan to have a deep defense, counter attack, medium support range, etc etc etc. Then make sure the CPU follows what is defined in the tactics/formations screen, that way, you might have a game where team play different styles.