The Mendoza Line is an expression in baseball in the United States, deriving from the name of shortstop Mario Mendoza, whose batting average is taken to define the threshold of incompetent hitting. The cutoff point is most often said to be .200, and, when a position player's batting average falls below that level, the player is said to be "below the Mendoza Line". This is often thought of as the offensive threshold below which a player's presence in Major League Baseball cannot be justified, regardless of his defensive abilities. Pitchers are not judged by this standard, since their specialized work and infrequent batting does not require as much hitting competence. The expression has been also extended to other realms to indicate a low-end cut-off point.
Origin of the term 
Mendoza, a flashy defensive player from Chihuahua, Mexico, played for the Pittsburgh Pirates, Seattle Mariners, and Texas Rangers and usually struggled at the plate. Mendoza was known as a sub-.200 hitter whose average frequently fell into the .180 to .199 range during any particular year — four times in the five years from 1975 to 1979.
The "Mendoza Line" was created as a clubhouse joke among baseball players in 1979, when from early May onwards, Mendoza's average was always within a few points of .200 either way, finishing out the season at .198 for the year (and .201 for his career to that point). "My teammates Tom Paciorek and Bruce Bochte used it to make fun of me," Mendoza said in 2010. "Then they were giving George Brett a hard time because he had a slow start that year, so they told him, 'Hey, man, you're going to sink down below the Mendoza Line if you're not careful.' And then Brett mentioned it to Chris Berman from ESPN, and eventually it spread and became a part of the game." Berman deflects credit back to Brett in popularizing the term. "Mario Mendoza — it's all George Brett," Berman said. "We used it all the time in those 1980s SportsCenters. It was just a humorous way to describe how someone was hitting."
Mendoza had two more full years in the majors, with a handful of plate appearances in 1982, ending with a career average over nine seasons (1974–1982) of .215. By that point, however, the phrase was already embedded in baseball culture.
Other uses 
The term is also used outside of baseball to describe the line dividing acceptable mediocrity from unacceptable mediocrity:
- "A sub-$2,000 per theater average... is the Mendoza Line of box office numbers..."
- "I don’t think you could find any other figure in politics who has run this far below the Mendoza line and still managed to get taken seriously as a presidential candidate."
- "Republican pollster Neil Newhouse... argues that these numbers have crossed below the political 'Mendoza line'..."
- "The U.S. 10-year note yield declined below 2%... before moving back above the Mendoza Line (baseball lingo for a batting average of .200), to 2.09% by early afternoon."
Alternate expressions 
Another expression used in baseball to indicate that a hitter is not being effective is "On the Interstate", which derives from batting averages in the .1xx range looking similar to the route designations of the Interstate Highway System in the United States, in which roads are referred to using "I" to indicate an Interstate Highway, and a number to indicate the specific route. Thus a batting average of .195 looks roughly similar to "I-95", and the batter is said to be "on the Interstate."
Because of the 15 point difference between Mendoza's .215 lifetime batting average and the .200 level that is often implied by the term, at least one fan has suggested that the "Mason-Dixon Line" (.204) be used instead because it is closer to .200.
- "Mendoza line" on Baseball-reference.com
- Dave Seminara (July 6, 2010). "Branded for life with 'The Mendoza Line'". St. Louis Post-Dispatch.
- "Mario Mendoza" on Baseball-reference.com
- The Numbers - Even Horror Films Can't Survive the October of Terrors
- Jonathon Last (via Andrew Sullivan)
- Mark Murray. "Republicans abandoning Bush". MSNBC. Retrieved September 1, 2011.
- Randall Forsyth (August 18, 2011). "Fear Sends 10-Yr Treasury Under the Mendoza Line". Barron's. Retrieved September 1, 2011.
- "Hitting on the Interstate" at Baseball-reference.com
- Brandon Gavett & Lee Ashendorf (May 2003). "The Fans Speak Out: Letters to the Editor". Baseball Digest. Archived from the original on 2011-06-23. Retrieved April 19, 2012.
- Pepper, Al. Mendoza's Heroes: Fifty Batters Below .200 Poco Press, 2002
- Dickson, Paul. The New Dickson Baseball Dictionary Harvest Books, 1999.