I don't use it at all for recruiting because of potentials, but I do occasionally use it to help set depth chart. If you truly value a key set of attributes for a player in a certain position, sometimes setting these roles and looking at your roster while viewing this will remove some bias you have towards certain players. Sometimes you'll be surprised by which guy is assumed to be best for a position based on the attributes you valued there.
Lets say I value my sg by importance spd, def, ath, per, bh, pass ( in % out of 100 - 20/18/16/16/10/10). I might see SG - A with respective attributes of 75/60/55/60/40/40 and SG - B with 60/65/50/65/50/50. With the eye test, I would probably go SG - A, but using my player role figures, SG- B might actually be higher rated. (I did not actually run this, but this is just to demonstrate the example)
An actual example using my set roles for my team is Gitlewski and Walker. From a quick look, I might say Gitlewski is better for either guard position because of the perimeter shooting, but using my player role settings shows that Walker is actually better at both positions and the gap between them is largest at pg.
In the end you still have to account for potential growth, IQ and personal bias and may choose to go against the ratings shown, but if you have a tough decision between 2 players, this could be one way to make the choice.