And that's the thing, and coincidentally getting back to the hovering baseball.
Looking at the overall rate is not informative. The overall rate is the sum of the forces acting upon it. If we have a decelerating car with the brake down, yet you step on the gas enough to maintain a constant velocity, you still have acceleration. You have enough to offset the deceleration.
The assumption made by people posting the historical data is that the rate is constant. What if the rate was decelerating, or should be decelerating, and then stopped decelerating to remain constant? Well if that happened, some accelerating force has come into play. But again, I haven't read the study, so I don't know what data they used or how the did their analysis. But the data shown doesn't yet contradict their conclusions, not in any obvious way.
I can measure the velocity and acceleration of a hovering baseball for hours and come up with zero, zero, zero zero. It doesn't change the fact that it is accelerating upwards at 9.81m/s^2. The reason it is hovering is because it is ALSO accelerating downwards at 9.81m/s^2.