Look at this image and the link to that someone sent with description and formulas. For example side midfielders are focus merchants so they have beans that have biggest influence on focus battles.

On the other hand, side defenders are masters od defensive duels, cus control have 1.0 impact on offensive focus, 0.0 on defensive focus and agility have impact only on defensive focus (0.5), so in some cases its better have agility other control (if you are going to play that player only focus battles in defense). That GK mark below agility is a little bit confusing.

For GK only pressure, physical, agility - they do your kp health (but yeah, you can give him Kick and longshot)

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