DOYKL - Your reasoning makes sense from a neutral statistical point of view however the critical point is that the WTS have been shameless in their massaging of statistics to demonstrate growth and imply the action of Holy Spirit and Jehovah's blessing.
They have consistently used peak publishers as a marker for gloating. Anyone who regularly saw the KM in the 70's, 80's and 90's would know how a country's yearly peak publishers was used to demonstrate growth, even when it bore little relationship to the monthly figures presented.
Examination of the figures over time has demonstrated completely different trends to those preferred by the WTS and they have slowly removed published figures from the KM and also from publications. You see significantly less gloating now, rather it's all about the money.
The Yearbook is pretty much the last place you will find the data needed to demonstrate the real health of the organisation and they are making moves to obfuscate that even more. The new reporting regime completely undermines the old argument of needing to know placement figures to gauge publishing requirements. It simply lumps everything together, encourages false reporting and includes meaningless preaching interactions. The object - find some way of having some growth in preaching related figures.
I am personally very surprised at the drop in hours given the fact you have people on carts doing 3-4 times what most do on the D2D work but I bet the number crunchers at Bethel saw that coming via trends from monthly reports and have tried to stem the flow with the new reporting instructions.
I also wonder if they will start to raise the profile of Matt 24:12 regarding the love of the greater number cooling off and apply that more directly to Witnesses