Of six by-elections since 2008, only one, Mt Albert, looks anything like Christchurch East in the scale of the Labour result.
It's no coincidence those two seats had similar results: They were planned and run on the same organisational template. None of the other by-elections were.
When you look at election campaigns, you can always tell the difference between the old pros and the amateurs. The amateurs usually talk about messaging strategy and images. The pros pay most attention to the nuts and bolts: How many people were working in the campaign? How many signs did they put up? How much paper did they deliver?