Design rotting?

[Roberts_Clif]

1. It appears as the Filament on the spool got tangled as the print progressed, At the top it appear that the extruder was having a hard time pulling filament.
2. It could be that the top of the model is under-extruded because over heating the filament could have caused a clogged hot-end.
3. The filament adsorbed moisture causing under-extrusion
4. I have seen times that a filament seem (Splice) caused the clogged hot-end.

Personally I would think that number one is the correct answer, as have had this happen many times and when I looked the filament had untangled itself.

And I am looking at the bottom image where the start of the print looks kind of ok, and progressively gets under-extruded.