The Dream Team star man is awarded for every point scoring Dream Team game. In a very similar way to a man of the match award, a star man is often the player who is deemed to have had the biggest impact on the game in question. The star man is awarded to the player with the highest rating over the course of the game and automatically picks up an additional 5 points.
In my experience the star man is often either an attacking midfielder who has scored or set up a couple of goals. Or a striker who has scored 2 or more goals. The star man is a very good way of picking up additional points. For example if a striker scored 2 goals in a game his point total would look something like this:
2 goals: +10 points
Star man: +5 points
7+ rating: +3 points
Making a total of 18 points. Having the main goalscorer at a top 6 club would be a great way of accumulating points.