Cause and effect.
It is not always what most people think. But it is consistent. On the other side of something happening, a cause can always be identified as if it was in the shine of a spotlight on an otherwise pitch black moonless night.
Often, affect hides the cause behind public sentiment.
Public opinion is swayed by bits and pieces of information that are assigned significance in an assortment of ways … none necessarily tethered to something that truly drives predictable results.
Going in, likely; coming out, certainty.
Even a contest yet to be decided that has a 99% probability of favoring one side in a two team race fails to offer an ironclad guarantee, but after a game is over one side is the 100% winner and the other a zero.
Certainty is only provided after a contest is decided.
The cause of something is most often tied to the need to perform at a higher level than recent outings. When a team in that sphere meets a team that has run a winning streak to it’s limits, an opportunity to cash a proposition most often comes with points on the spread.