The ignition system:
Loss of 12v ground while the engine is running will fry the diodes in 40-225 hp Mercury switch boxes and 25-225 hp Johnson Evinrude power packs in a heartbeat. It doesn't have to be a broken circuit, just a momentary dip in voltage less than 10.5v will overheat the diodes and/or capacitors inside the switch box, not because of the low voltage (pressure) but from the lack of a strong grounding circuit.
If when the diode leads melt they happen to melt into the ground lead inside the switch box/power pack then it will also take out the stator.
When you hear someone say "it started running like crap and as we were limping back it just died and wouldn't restart".... That is usually what happened.
The charging system:
A stator has two separate sets of coil windings, one powers the ignition system and the other is either rectified and/or regulated and recharges the battery at either 16 or 40 amps after each starting cycle and also each time you touch the tilt/trim switch. As soon as the regulator senses the battery has returned to full charge then it directs all charging voltage to ground to prevent over boiling the battery. A battery that is failing will never actually reach full charge but the stator and VR do not know that, all it knows is that the battery will not accept the charge so it just switches stator voltage to ground and only attempts to recharge when you either first start the motor or hit the trim switch (dips in voltage are what trigger the diodes there). After awhile of running like that one of two things happen...either the low battery voltage causes heat in the two yellow VR wires and causes them to melt into a ground (can cause an actual fire), or the battery gets so low that it momentarily reverses polarity causing the dreaded loss of ground which takes out the VR and the charge coil winding side of the stator.
Whew! Now aren't you sorry you asked?