player performance and team performance improves with better IQs - IQ affects performance. Better IQ is better. Worse IQ is worse. Very bad IQ hurts significantly.
An important comparison to make between your team and your opponent is your depth in terms of IQ - if you have say 9 guys at B+ and above and he has 9 just three such guys, you may want to go uptempo and you may want to target his low IQ defenders. All things being equal - every step is multi factored,.