Still confused. I have 2 "ST" playing at the same time. One with 4* uses blue arrows and gets better value at the end of the match than the other with 5* and red arrows. But the player with red arrows scores much more times (and receives more yellow cards) than the first one.
Seems that red arrows in attackers means more aggresive and blue arrows more pasive. Not a clue what exactly means for the engine.