One important thing to keep in mind - I should add this to the fatigue FAQ - is there is a critical difference in the way fatigue works for position players versus pitchers.

For position players, fatigue is in some ways self-correcting.  As players fatigue, they play worse (in theory).  So their OBPs should decline, meaning they accumulate fewer PA, and therefore their rate of fatigue slows down.

For pitchers, in contrast, fatigue exacerbates itself.  As pitchers fatigue, they play worse (again, in theory).  So they give up more baserunners, and throw more pitches, and fatigue gets worse.

It is for this reason that I am much more concerned with having enough IP on my teams than enough PA.  Drafting too few IP for your cap/park is a good way to dig yourself into a hole you may never get out of.

Position player fatigue impacts offense very little... it affects defensive play much more significantly... in my (limited) experience with position player fatigue at least.

The more outs he makes the less likely he is to get additional PA in any given game.

I have seen position players continue to hit well against my team even when fatigued.  If you have a poor fielding hitter, it might matter more as he will make more errors when fatigued.  Pitchers, usually putting them out there when fatigued is not a good idea. 

WIS published a curve years back on the actual performance drop off expected in hitting....if I recall, it was down around 90 - 92% before much drop off in hitting happened. Maybe someone else saved that curve. I can't find the article in the search.

Now for a point of comparison, mlb98800 is just starting. After 2 games, No one is fatigued. I have Joss and Ford as the anchors of my rotation, Joss will be at 100% for his next start.

This ia all very interesting. I start off with 4800-4900 pa's and 1200-1250 ip's for OLs @ Coors...with AAA going in to rest the starters and the occassional $200k WW starting pitcher, my guys are always fine.