Look at this image.
It is a continuous line graph for a set amount of time, 28 days in this case.
The day after this image is taken, the data point at the end will no longer be in the 28 day range, the data point in front of it will take its place, and a new one will be made for the far right.
If a data point on a specific day shrinks, it's important to note that earnings are always listed as estimated.