I have used this same pitching staff several times in 120m cap leagues, with good success each time. But, in the current season this staff is playing, fatigue has been a total non issue. Usually, the fatigue is manageable, but present.  '08 joss and '09 mathewson, in particular, have pitched more innings, to this point in the season, than ever before, because fatigue issues forced me to move them back a day, or skip a start. But in the season I am playing now, they are sailing right thru. Not that I am complaining, but I wonder if anyone else has experienced anything similar to this? Any comments or explanations? Several of my relievers hardly ever get into a game.

is it the same theme? different theme restrictions result in different kinds of hitters drafted, and so you wouldnt need the same IP. are opposing hitters of the same quality? maybe you just got placed in a league with pitching dominated teams. same ballparks? same defense? if nothing is different it's probably just dumb luck.

Avoiding extra innings or games where your starters get pulled early helps, especially in the first week of the season.

If you're talking about the Choose Your Own Theme league team, that staff is only throwing 122 pitches/game so far, so they've been really efficient and getting more IP out of fewer pitches.  That's a big help for fatigue.  I like my pitchers to average around 135 pitches/game.