At what fatigue percentage

Do players take themselves out of the game?
An injured player is automatically replaced at the next phase. But there is no subs for fatigue. It's a thing you can manage if you are online during the game.
Ah, and does fatigue play a major factor in the game? Such as slower moving players or more likely to get injured? Thanks for the reply!
During a game, every players skills are multiplied by (0.5 + energy * 0.25 + moral * 0.25 + match_bonus)
ok, good to know. So, following this equation: 1.00 morale and 1.00 energy means that a skill of 60 would stay at 60, not counting any match_bonus addition. Which means that any lessening of energy or morale lowers your skills, right? 1 * .25 (100% energy) = .25, 1 * .25 (100% morale) = .25. Sum is .5, which is then added to .5 and equals 1.
Exactly
Just to clarify: the morale loss is proportional, not just a + if happy or a - if unhappy, right?
yes according to the math it's proportional. That's why it's the best to keep morale maxed and play with need perfect energy. Not always does that happen but I just increased my team's stamina across the board with some quick training.
Maybe I should start paying my players better
Had someone telling me the morale boost is a pure +/-, so wanted to confirm before paying my players crazy salary lol

I'll probably still roll with lower salary most of the time.