The question is incomplete. Based on the full question, it is statistical.
This is an excerpt from Stephen Levitt and Stephen Dubner's Freakonomics.
The excerpt gives the statistical data of the wrestlers. The win-loss percentage between 7-7 wrestlers and 8-6 wrestlers is judged when either one of them is in the bubble the next time.
There will not be pressure in the individual match. They win only 40% of the rematches.
The reason may be to show the reader that this is important and to give the word an emphasis. It also gives the reader a feeling of someone being watched just 'perching above my chamber door".
