BYU beats a highly ranked team. Defeated team goes on to have a poor season.
Was it
1) The defeat to BYU demoralizes a team and initiates a cascading decline resulting in under-performance for the remainder of the season. (For which there are numerous apparent 'examples')
OR
2) The team really wasn't that good in the first place, and BYU caught them when they were down and exposed them for what they really were. (For which there are about the same list of apparent 'examples')