There is a simple formula I use for position players to determine how many plate appearances a player can have during a season. If a player plays the entire season it is about 730 plate appearances, plate appearance is not the same as an AB by the way. If you take 730 and multiply it by the players durability as a percentage, it will give you the approximate number of plate appearances a player can have during a season. EX: 730 x .84 = 614. In the case of Charles Bottalico, he has already had 506 plate appearances. Although that is not quite 614 but his fatigue level will drop because that number will be grossly exceeded before the end of the season at the present rate. It leaves him about 108 plate appearances (or about 24 games, divide 108 by 4.5) til the end of the season as there are 46 games left. To get his fatigue level back to 100% it may take about 10 to 15 games or more.
The rule of thumb I use during the season is to rest a player periodically like so:
90 or above - rest once every 15 to 20 games. Equates to about 10 playing days off.
80 to 90 - rest once every 10 games. Equates to about 16 playing days off.
70 to 80 - rest twice every 10 games or so. Equates to about 32 playing days off.
below 70 - rest once every 5 to 8 games. Equates to about 40 or more playing days off, normally for catchers or low durability bench players.
Also, players in the top half of the batting order will see more plate appearances and fatigue more quickly than the bottom half. It is better to rest them during the season because they are needed most at the end of the season especially during a playoff run. If the fatigue level drops below 100%, I try to rest them for two days or I end up using them every other day.
Adverse effects on fatigue is a player will not play as well and is susceptible to injury. For the minors it says that fatigue will help increase a players durability during rollover, but do you risk injury to a future superstar player for that reason? I try not to allow minor league players to drop below 95% as a rule, it just isn't worth the risk. Another thing I don't pay much attention to in the minors is playing players out of position. Maybe not the coolest thing to do, but it is better to rest a player than being forced to do it anyway because of injury.
If you are wondering how you can find out the number of plate appearances a player has: Go to Stats/Awards in the World drop down and click on Player Statistics and use the Extended function in Batting.