Fatigue & Resting Players

Baseball players experience two types of fatigue: day-to-day (short-term) fatigue and seasonal (long-term) fatigue.

Day-to-day fatigue occurs when players play without a day off.

Position players recover well after a day or two off, while pitchers may need more rest depending on their workload.
All players experience fatigue when they play, and they rest on their days off.
Each player has a current and maximum endurance.
When a player is fully rested, these values are the same.
All players lose current endurance points when they play, with higher endurance players fatiguing proportionally more slowly than players with lower endurance.

Seasonal fatigue is the overall wear-and-tear of the baseball season.

A player's endurance determines how much they can push themselves before experiencing adverse effects.
Players with high endurance can play almost every day without adverse effects, while players with low endurance cannot play as many games at full strength.
Season fatigue temporarily lowers a player's effective maximum fatigue level.
It increases the time it takes for a player to recover. Players with high season fatigue will recover less on a day off.
Resting a player can reduce or eliminate season fatigue and restore their maximum fatigue level.
If a player doesn't regain all their endurance as expected, they may be suffering from season fatigue.
Note: Using designated hitters (DH) causes less potential season fatigue than playing a position. Toggle your use of designated hitters to rest players with low endurance.

Each player has a status that reflects how rested they are.

The status levels as players get more fatigued - Rested, Good, OK, Tired, Fatigued, and Exhausted.
Performance penalties, in the form of reduced effective ratings, begin when a player is tired and increase until they are exhausted.
Exhausted players will not start games, and pitchers will be removed from the game if possible.
All skills are subject to performance penalties when a player is tired, except for EN (endurance) and SY (synergy).

All position players fatigue when they play, with catchers fatiguing faster than players at other positions, and designated hitters fatiguing slower.
Pitchers fatigue based on their pitch count, losing about one point of endurance for every two pitches. For example, a pitcher with 50 endurance can throw 100 pitches before becoming exhausted and being taken out of the game if possible.

Players will recover current endurance at a rate of about 1/4 of their maximum endurance.
This recovery rate gradually decreases as players accumulate season fatigue.

Manually adjust your roster to ensure how much a player plays.
Platoon your players by changing your lineups against right-handed (RHP) and left-handed (LHP) pitchers. Rest players by using right-handed hitters against left-handed pitchers and left-handed hitters against right-handed pitchers.
Set your manager settings to automatically substitute players when they fall below a certain fatigue threshold. Adjust the "rest player" sliders to rest players sooner when they are tired. Players can rest in AAA, where they are guaranteed not to play.