There is a certain logic how the arrows get created. I've seen it once surely, my memory only retained the idea not to look into it again.
Various inputs are factored but not necessarily all to catch what's going on. E.g. during descent to FL 100 the arrow only indicates the point where the aircraft would have slowed down to 250 kt after reaching that level.
The scenario when climbing VS+2000, speed has dropped to 260ish and the managed target is still 290 kt, for instance, would be a one when the hockey-stick is surely meaningless.