- When a fielder illegally hinders a baserunner. He does not need to "get out of the way" while he is fielding the ball or actually has it (and can tag).
- See on-base percentage.
- A batter who goes hitless in a game, as in 0 for 4 (spoken as oh fur). Also wears the collar or "takes the collar."
- A game that can be considered complete. If more than half the game has been played before being ended, or "called", by an umpire, it is considered official and all records from the game are computed in the players' and teams' statistics. For a nine-inning game, five innings need to be played, or 4 1⁄2 if the home team is winning. An incomplete game can be either suspended or replayed from the first inning.
- The official scorer is a person appointed by the league to record the events on the field and to send this official record to the league offices. The official scorer never goes on the field during a game (but typically watches from the press box). The official scorer's judgments do not affect the progress or outcome of the game but they do affect game and player statistics. For example, only umpires call balls and strikes, whether a batted ball is fair or foul, whether a hit is a home run, and whether runners are safe or out. But it is the official scorer who determines whether a pitch that got by the catcher is a wild pitch or a passed ball, and whether a batted ball is a hit or an error (or a combination of the two); likewise whose errors, put-outs and assists are whose.
- A day when a player performs below his normal level, whether due to illness, bad luck, or other factors. "Bonderman had an off-day and didn't have good command of his breaking pitches."
- A day when a team does not have a game scheduled. During the regular season, Major League Baseball teams almost always have games scheduled on Fridays, Saturdays, and Sundays, and they may need to travel between series. Off-days tend to occur on Mondays and Thursdays.
- A pitch that is significantly slower than a given pitcher's fastball. Typically, a curveball or a change-up.
off the hook
- When a team that is behind ties the game or takes the lead, the pitcher who would otherwise have been credited with the loss is said to be "off the hook".
off the trademark
- When a player hits the ball off the middle of the bat, where the manufacturer's trademark is usually placed, resulting in a weakly hit ball. Usually the result of a pitcher jamming the hitter.
- Overall Future Potential (OFP) is a scouting assessment of a young player's potential as a future major leaguer, scored from 20 to 80. The criteria are different for pitchers and position players. See also tools.
ol' number one
- A fastball. From the sign the catcher gives for that pitch.
- When a batter strikes out five times in a game. This same dubious achievement is also called a platinum sombrero.
on a line
- When an outfielder throws the ball directly to an infielder or the catcher without relaying it or bouncing it, he's said to "throw the ball on a line". Usually used when a strong throw beats the runner and gets him out. "Jack Barry, however, made a running stab to grab the ball and threw on a line to McInnis for an out."
on-base percentage (OBP)
- Percentage of plate appearances where a batter reaches base for any reason other than an error or a fielder's choice.
- The next batter due to bat after the current batter. The area designated for the on-deck batter is a circle five feet (1.5 m) in diameter, officially called the "next batter's box" and commonly called the "on-deck circle". Ironically, the on-deck batter rarely stands in the on-deck circle.
on his horse
- Running at full speed, especially in reference to an outfielder tracking down a fly ball.
on the black
on the board
- A team is "on the board" (the scoreboard) when it has scored one or more runs. "After being shut out for six innings, the Sox are finally on the board." White Sox announcer Hawk Harrelson also uses the phrase as part of his home run call: "You can put it on the booooard ... YES!"
on the farm
- When a player is playing in the minor leagues, he is said to be spending time "on the farm". It refers to a team's farm system.
on the interstate
- A player batting between .100 and .199 is said to be "on the interstate". The term refers to the fact that a batting average in the .100s can resemble an interstate name (e.g., .195 looks like I-95, especially on older scoreboards). A hit to put an average above .199 gets a batter "off the interstate." A batter whose average is below .100 is sometimes said to be "off the map". See also Mendoza line. Players in the majors who spend too much time "on the interstate" will most likely be demoted to Triple-A.
on the ropes
- When a pitcher appears to be tired or lost command of his pitches, he may be said to be "on the ropes" and about to be replaced by another pitcher. The term likely derives from the sport of boxing, in which a fighter who is being beaten up or dominated by his opponent may lean against the ropes to keep from falling to the mat.
on the rug
- A player is said to be "on the rug" while playing a ball in the outfield on artificial turf.
on the throw
- A defensive attempt to put out a baserunner attempting to reach more bases than the type of hit would typically allow, such as a runner on first attempting to advance to third on a single.
- Also refers to the successful advance of a baserunner while such a play is being attempted on his teammate. See also: fielder's choice.
- A batter who safely reaches first base but is tagged out attempting to reach a subsequent base on the same play is credited with a hit for the number of bases he safely reached, but is said to be out on the throw.
- Example: With Abel on first base, Baker hits a base hit to center field. Abel easily reaches second and tries to advance to third, but the throw from the outfield is in time and he is tagged out by the third baseman. Meanwhile, Baker has safely reached second base. Abel is out at third base on the throw. Baker has a single and advanced to second on the throw. The next batter, Charlie, hits a double to the center field wall, allowing Baker to score from second. Charlie safely rounds first and second base and attempts for third, but the throw from center field is in time and Charlie is tagged out at third base. Charlie is credited with an RBI double, but is out at third base on the throw.
- A player who appears in just one major league game, plays respectably, and then is either demoted to the bench or back to the minors.
- A game in which one team was limited to one hit, a great feat for a pitcher. Batters may have reached base via walks, errors, or being hit by a pitch. See also no-hitter and perfect game.
- A traditional relief pitcher who starts a game for strategic reasons and is replaced early in the game, usually after the first inning, by a pitcher who is expected to last as many innings as a true starter.
opposite field hit
- A hit to the "opposite" side of the field from the direction of a player's natural swing, i.e., a left-handed batter who hits to left field or a right-handed batter who hits to right field. Also known as going the other way. See pull hitter.
OPS (On-base Plus Slugging)
- A term recently invented by statheads to measure of a batter's ability to produce runs. Obtained by adding slugging average and on-base percentage.
- Defined in MLB Rule 2 as "the effort that a fielder of average skill at a position in that league or classification of leagues should exhibit on a play, with due consideration given to the condition of the field and weather conditions." A defensive player's ordinary effort is considered by the official scorer in making certain judgment calls, such as hit vs. error or wild pitch vs. passed ball.
- The type of pitch that a pitcher relies on to get an out, often his best pitch. Headline: "Angels Notebook: Rodriguez embraces change as out pitch".
- An outfielder is a player whose position is either left field, center field, or right field. See position.
overpower the hitter
- To throw a pitch that is so fast the batter cannot catch up to it with his swing. "And eight runs were more than enough offense to back Wolfe, as he continually overpowered hitters with his blazing fastball. Santa Clara hitters just couldn't catch up to it."
- A baseball vernacular term synonymous with "shift", either an infield or outfield shift. The fielders shift to occupy the areas a particular batter is thought to typically hit.
- When a fielder throws the ball so high that it sails over the head and out of reach of his target. "Sean Halton struck out, but the catcher couldn't hold onto the pitch, and then overthrew first base, which allowed both Martin and Greene to score."
- If a thrown ball goes over the head or wide of the infielder and sails off the field of play into the dugout or the stands, the umpire will rule an overthrow and allow the runner to advance one base.
- A pitcher who throws the ball too hard to control it well is said to be "overthrowing the ball". "Gardenhire said Crain, demoted to Class AAA Rochester earlier this season, is pitching with more confidence and, most importantly, he's not trying to overthrow the ball."
- Before 1980 this person was typically a local sportswriter; beginning in 1980 the League hired "independent contractors" for the job. For an informative article, see David Vincent, "The Official Scorer", The Baseball Analysts, Aug. 18, 2005. On more recent changes see also David Laurila, "Scoring the Hits and Errors – Official Scorers in the Post-Season", BaseballProspectus.com, October 10, 2007.
- Richard Adler, Mack, McGraw and the 1913 Baseball Season (2008), p. 258.
- Miller, Sam (October 4, 2018). "A brief history of bullpenning". ESPN.com. Retrieved October 4, 2018.
- Allan Steele (2008-06-29). "Angels Notebook: Rodriguez embraces change as out pitch | Sports | Baseball | PE.com | Southern California News | News for Inland Southern California". The Press-Enterprise. Retrieved 2010-06-29.
- Palo Alto Daily News
- KOZE-Sports.com (2008-03-15). "LCSC sweeps Corban to stretch win streak to 14". Koze-sports.com. Retrieved 2010-06-29.
- "Twins' Justin Morneau returns to Minnesota to see specialist about dizziness: First baseman to see specialist about dizziness | LexisNexis | Professional Journal archives from". AllBusiness.com. 2009-08-21. Retrieved 2011-12-06.