"What does that have to do with the price of tea in China?" is not specific to sports journalism. Wikipedia has a page that covers such phrases:
"What's that got to do with the -- ?" is an expression which is used to denote something which is unrelated to the current topic of discussion.
A common form "what does that have to do with the price of tea in China?", is a retort to an irrelevant suggestion. This facetious usage implies that the topic under discussion might as well be the price of tea in China for all the relevance the interlocutor's suggestion bears on it. It has been said that this expression has stemmed from economists, who describe everything economic as affecting everything else, trying to find an expression which denotes the farthest logical connection from their current economic focus, in a sort of butterfly effect. In this way, the price of tea in China was used to denote the farthest possibility. It can also be used to denote an irrelevant topic.
In other words, it is a rhetorical question used to point out that a previous statement is irrelevant or insignificant. Other variants include:
- What's that got to do with the price of eggs?
- What's that got to do with the price of fish?
- What's that got to do with the price of cheese?
The wiki also notes that the tea in China variant might have been derived from another similar idiom, "all the tea in China".