in one of the Q&A's with the developers, they mentioned in an off-comment that the most important skills for the goalie is the Defensive ones...but that Mental skills are important too.

They didnt even mention the attacking. And why would they? Why good does it do a goalie if he knows how to score, shoot, pass and dribble? Absolutely nothing. I always train my goalies only in defensive and mental; and they are doing great.