Something me and a friend thought about when playing. Me and him never have high scorers because we never play our starters more than 32 minutes to give them rest. So my question is does player fatigue rollover into games/weeks? Or can I go balls out and just play my starters 40 minutes and game and not worry?

no, it doesn't. I'd like to see this enter into tournaments a bit where games on played on consecutive days, but at this point it doesn't happen. 1st half usage doesn't roll over into the 2nd half either. Unless your starters have 9 or 10 current Athleticism, however, their performance will suffer considerably by the end of the halves if you are playing them 40 minutes/g. Pace and pressure of both teams comes into play with that as well.

My 'impression" is that when players get very fatigued, they are more prone to committing fouls and the likelihood of an injury goes up a little. This is not something that I can prove or that I know for sure...it's just been my gut-feel for what I have observed when playing out games. And are they worse defensively? Again, very hard to know for sure.