It means he has an 80% chance of playing at his maximum technical/mental ability (physical ability is not affected). Even with max consistency, he will still take a technical/mental ability penalty about every 5th game, but the actual amount of this penalty can vary. Low consistency doesn't necessarily mean a player will have poor form, and high consistency doesn't guarantee that a player will always turn in good performances. A player's personality, overall ability level and suitability for his