I said "must be". I don't know why, or whether in fact there is. All I know is the control columns move the elevators (eventually). I've seen it for myself in the last couple of days by looking at the elevators (one with a stiff tailwind), and every time we do a control check prior to takeoff on the cockpit elevator display. Turn the EPAS off and I suspect the elevators would still move down.
In this accident, I have no doubt, assuming all these tails are the same, that pulling full backstick before startup would have had the left elevator responding and the right not (because it was jammed).
In any case, it'll be interesting to see how Boeing and the FAA respond to the NTSB's recommendations.