Mixed is best, I have tested both short/long.
Mixed helps the engine to favour you. How? I think it weighs your players' mentality.
and the higher their mentality the more "luck" u get in terms of your team having discretion
and apply timely passes(knowing when to use long,short,or through balls.
For instance, when I tried long passes, game possession switches against me,
more like they throw caution into the win and keep using long balls even though the opponent keeps cutting it off.
When I tried short passes the commentator just wasnt active, my players went into tic-tac mode and it was hard
to tell who has the ball or who is doing what, in fact, it was hard to see my player dribbling, and there were little or no long range shorts.
For me mixed is better, especially with force counterattack.