Anyone disagree with me, feel free to say so. These are just my observations:
Obviously the SP goes as long as you want, pitch counts and pull rating determine. The sim coach won't pull him before his target count unless he's getting lit up and his pull rating overrides it.
The LR comes in if the SP hits either his max pitch count or pull rating, and if no Setup RPs are available for the inning. LRAs before LRBs, unless you are trailing by a lot (not sure what the sim coach threshold is - 3, 4, 5 or more runs) in which case the LRB comes in. I don't ever use Mopup, so I have no real idea what they do.
The logic behind SetupA seems to be that the SuA goes in if you're close or ahead in whatever inning you set them to come in, assuming the SP has hit pitch count. I'm not sure the exact trigger, because I've seen Simmy put the SuA in before the SP hits max pitch count. So maybe it's a combination of pitch count and pull rating? Setup As come in before SetupBs, but again, if you're trailing by too much, the SuB comes in first.
Closers come in when you set them to, . However, one thing I've noticed is that if you set all your best RPs to SuA, the sim coach seems to save the best one for the save opportunity. Again, I could be wrong, but I've seen it happen that way, that the best one doesn't come in first.
Again, those are only my observations. But that's why I appreciate strikeout26's idea. By setting a SuA to come in in the 4th inning, you're putting him in line ahead of any other pitcher as long as your team isn't getting blown out. That's why the comparison pitcher in the 3rd post can rack up 27 wins. Essentially he's a semi-permanent Tandem B.