At the point where Oriole "nerfed" completion percentages for deep/very deep passes these passes were being completed at the same clip that short/medium passes were. No matter how accurate/strong armed a QB is the percentages go down the further the ball is thrown. The longer the pass is, the longer it takes to develop which should increase sacks/pg.
If someone is throwing Very short against a cover long...that should lead to higher completion percentages. If someone is throwing deep/very deep against a cover short that should also increase completion percentages. But now that I (and the rest of us) can't just test out different settings to determine how much of the cause is settings based and how much might be engine based we rely on oriole to do the testing on his own.
My fear is that we complain about the comp% of running backs so much that the next unrealistic thing is setting cover short against running back passes leads them to not only be lower completions, but makes the whole part of the game irrelevant. That will in turn cause overall completion percentages to go down unrealistically, and then everyone will clamor for better comp% for QB's which will lead to medium/deep passes being too powerful.
I do not envy the Job Oriole_fan has now. I want to do the legwork for this like I have in the past, but while last I checked the beta site was still up, it is not under the same engine that is currently in the live game. I think I am seeing some of the throttling that slid64er is talking about too, but I'm just not sure.