One thing I find frustrating is having no system showing how players are actually performing during a match(can't imagine it would be too difficult).
For instance, you decide to change formation (or just make a substetution) only to find after the match that the MC you took off was performing well, and you maybe left on the worst performing MC. This is unrealistic, as in a real match, a manager would take off the worst performer on the day if given the choice.
Anybody else think this would help?