I have noticed this very much so. It depends on your style of play. For example, level 4 teams do not defend aswell as level 5, but are more direct with the way they play, aka they will try and beat you in more simplistic ways. Interesting thing i tried. I have played a CPU vs CPU watch on both level 5 and level 5, the level 5 match was 0-0 the level 4 was 3-1, same teams, same fitness. Level three is more long ball, which is easy to defend against, but on mall three levels,they put their chances away.