I don't use a water wiggle but the water wiggle should be sitting on the floor the same as the eggs would, the point is that the temperature is inserted into the center at the same height (or close enough) as the center of your egg would be to replicate what the temperature should be inside the egg.
Thing is, when it's sitting on the floor, it flattens out and the probe is well below the center of the eggs.
I'm going to try setting it on a scrap of wood to see if I can get the center of the water wiggle at about the same height as the center of the eggs.