It's been my experience with the bullpen setting that it's opposite of what you think.

An aggressive setting will mean that the manager is aggressive in letting his starters stay in longer.

A conservative setting will mean that he'll be quick with the hook if they get into trouble and not be willing to risk a big inning.

In my 4yrs of PB, I have always used a 4 man rotation and the robot routinely pulls my starters at 3 or 6 BFA left (depending on their recovery rate (9 or 8). I accomplish this with setting them all as Ace Starters and putting the "bullpen" setting on aggressive.

Try it out next away series.

Jon, STL Trash