One on ones – deal with opposition threats (SK and GK)
If the opposition team have succeed to break the offside trap, the goalkeeper is the last person to prevent the other team from scoring. The opposite player may have excellent dribbling and technique, which makes him a real goalscorer threat.
A good goalkeeper needs great attributes in bravery and decision to deal with these situations in additional to one on ones.
The goalkeeper attribute one on ones predicts how well the goalkeeper is to deal with these situations, and is partially linked to rushing out. One part of this attribute is the goalkeepers ability to deny scoring opportunity but also his ability to read the arising situation and predict what the opposite player might do (read: anticipation).
High one on ones attribute will increase his tendency to attempt to win the ball with confidence and impose these types of situations to his benefit. The goalkeeper may need good reflexes and balance in these types of situations as the opposite target may be an excellent dribbler or quick on his feet.
With a deep defensive line, this attribute will not be as important than if you play with a high defensive line.
Source:
Football Manager Goalkeeper Attributes | Passion for Football Manager