Does fatigue have a negative effect on defense and range, or just on hitting?

i'm not exactly sure on the exact numbers and when they happen. but i believe defense takes a hit more than hitting does.

Caution: observation only, no data.

It seems like I see hitters all the time in the 90s hitting like they always do. It also seems like there's a steep rise in errors once a player goes under 100.

i agree with llama, and especially with catchers

i'm also with llama. it's more of an impact on fielding than it is on hitting.

I'm sure it effects fielding, but to what degree I have never analyzed or quantified. I recall a player (may have been biglenr) who put together an infield with 4 RL players in an attempt to have an error-free season from them. they each had a 100% fielding percentage in real life. Things were moving along well; his players weren't making ANY errors until he let Placido Polanco slip below 100% fatigue by accident. Voila. He made an error.

My experience: higher fatigue no great drop off in hitting, but a definite rise in errors....

I definitely concur with the position that fatigue plays a bigger role on a player's defense as opposed to his hitting. I say this from experience inasmuch that I've had several cheap, low PA guys (60-100 PAs) going 3 for 4 in games, including home runs, while playing at between 40-60% while fielders start making errors at a much higher frequency when barely below 100%.