They aren't a prediction about who will be able to beat who on any given Sunday.
What they do, or at least attempt to do, is add in strength of schedule and margin of victory so that apples are being compared to apples.
If people want to look at this measure of past performance rating and use that to make predictions, they can. But success is not guaranteed.
Stronger teams beat weaker teams more often than the reverse. So says Captain Obvious.
This is an attempt to measure who has indeed performed as the stronger team to date.
Ramily!
