So you want a reliever, say Shields, who didn't start, with his 650 OPS, to have a 1235 OPS? That is 90% worse.

I'd say a 20% degradation is more than enough. That would give him an OPS of 780 if he starts.

I'd also limit him to 20 BFA ILO 30 BFA.

Remember the reason relievers can start is if the robot needs to choose a pitcher(for unmanaged or managed team), sometimes it needs to pick a reliever. Your idea would severly hamper the robot.