I consider 1200 the minimum for leagues with AAA and 1300 the minimum for leagues without, never throwing a tired pitcher.
Of course, that assumes a pitching friendly park, and good pitchers at $80m.
The good pitchers part may need to be explained:
You buy pitchers by IP. But, in the sim, they fatigue by pitches thrown. The sim will take the number of IP/162 that a pitcher has, and then multiply that by a number based on his hit rate, walk rate, and K rate. High BB/K pitchers get more pitches per inning than low bb/k pitchers.
So let's say that you have 2 200 IP pitchers. One with a 1.0 whip, one with a 1.30 whip. And let's say that each has a Pitch to inning multiple of 12. You set these guys in a 4 man rotation at 80 - 85 PC.
The better pitcher will face about 4 hitters ber inning. Say 3 pitches per batter, or about 12 pitches per inning. At 12 pitches per inning, he's going to pitch about 7 innings for you.
The worse pitcher will face about 4.3 batters per inning. Same ratio, is about 13 pitches per inning.. Or about 6 innings in a game.
Assuming he's starting every 4th game, that's 40 starts, or 40 extra innings required of your team for having a 1.30 WHIP 200IP starter instead of a 1.00 WHIP 200 IP starter. Realistically, things don't work out that perfectly, so maybe it's only 20 extra IP required of your team for having the worse starter. In any event, worse pitchers require more IP from your team. Most of us don't notice this, because we have a fairly large IP cushion.
So while you bought the same amount of IP, you actually don't go as deep into a game with poorer pitchers. So you need to buy more IP.
Same impact with using a pitching friendly ballpark, or really good defense. Fewer baserunners = fewer pitches thrown = fewer IP needed. It works in reverse in higher cap leagues... The calculation of Pitches to IP is based on $80m leagues, which are nearly all-star level teams. Once you go up to the all-time all-star level, your pitcher with a 1.0 real life WHIP starts throwing like he has a 1.4 WHIP, and he sees more hitters in a game, which means he doesn't last as long at a higher cap.