In modern usage, inside baseball is a figurative adjective meaning appreciated by only a small group of insiders or aficionados. It also serves as a noun denoting inside-baseball matters. The term is usually used in politics, where the inside-baseball business includes the sorts of things political strategists think about but which the public is not necessarily privy to or interested in. But it works in any context where the details of a subject are too technical or uninteresting for most people to appreciate.
In the late 19th century and the early 20th, inside baseball referred to a baseball strategy focusing on successful execution of small offensive plays such as bunts, stolen bases, and walks, so that scoring came from teamwork rather than individual heroics. In today’s baseball, the ideas and strategies of inside baseball are covered by terms such as small ball (i.e., small plays meant to produce runs) and Sabermetrics (i.e., a statistics-based approach to fielding teams), and inside baseball is used mostly outside the sport.
Exactly how our modern sense of inside baseball developed from the strategy is mysterious, but it could have to do with the fact that many of the plays emphasized in inside baseball are boring to casual fans, or it could relate to the importance of statistics and insider information in the inside-baseball strategy. In any case, the phrase has carried its modern sense since around 1980. It is primarily an Americanism.
We hyphenate the phrase when it’s an adjective preceding what it modifies and leave it unhyphenated when it’s a noun, but there are other approaches. We find many instances of the phrase in quotation marks, as both a noun and an adjective.
Political events in the nation’s capital are usually viewed in terms of inside baseball, tricky deals and economic log-rolling. [The Hour (1981)]
It may seem the ultimate in inside baseball, but the race for minority whip in the House of Representatives is providing some of the best theater on Capitol Hill these days. [New York Times (1989)]
To be sure, there are some inside-baseball scenes showing the editorial finagling and finessing that go into producing a story. [Washington Post]
There have been a few solid inside-baseball accounts, including one at the Vulture website that actually predicted that Universal marketing chief Josh Goldstine would lose his job because of the poor performance of “Battleship.” [LA Times]
It’s that time of the campaign season when journalists write long inside-baseball accounts of who does what inside a presidential campaign. [Guardian]