Looking deeper, this seems to explain everything except the ugly Exeter patches. It's certainly as close to a satisfying answer as we're likely to get.

@Dreamwalker I'm sure there is. But my search didn't find anything. I will, of course, keep looking.

I agree with this answer. However, the Hogwarts example is a slightly different situation, because it has been established in the books that the league is based on total points scored, rather than W/L/D, so losing narrowly is objectively better than losing badly. This obviously isn't the case in the World Cup final, where a narrow loss only feels better than a humiliating one.

@Paul It's definitely been used as a delaying tactic, but that would also work via audio or text. If the crew try to delay their foe to give them time to prepare a surprise attack, but are spotted in the act, thus spoiling the surprise, that would be more interesting.

@JeremyFrench I'm happy to edit the title. It was chosen to reflect my intent in asking this question, while the body narrows this down to something answerable rather than speculative and opinion-based.