Many will be misled once they have encountered the phrase "Mendoza line", probably they will think of it as a point on a map. For baseball players these two phrases are not new to you. The Mendoza Line is an informal term used in baseball for the threshold of incompetent hitting. Even though Mario Mendoza's lifetime batting average is .215, the Mendoza Line is said to occur at .200, and when a position player's batting average falls below that level, the player is said to be below the Mendoza Line. It is often thought of as the offensive threshold below which a player's presence in the Major Leagues cannot be justified despite his defensive abilities.

National League pitchers are not held to the Mendoza Line standard, since their specialized work and infrequent batting excuses less competence in hitting. American League pitchers do not bat at all, except in away-games against National League opponents. Such an average isn't worth installment loans or short term loans to keep in the team.  A Mendoza line batting average is something most major leaguers will put quick cash and extra effort into avoiding.

Further reading here http://personalmoneystore.com/moneyblog/2009/08/13/mendoza-line/ about the article.