Major League Baseball Uniforms - Official Rules

Official Rules

The official rules state that:

• All players on a team must wear identical uniforms during a single game.
• Numbers: All players must wear their uniform numbers on the back of the uniform. Further information: Uniform number (Major League Baseball)
• Undershirt: If the undershirt is exposed then all the players on the team must wear matching ones. Numbers or other devices may be worn on the sleeve of the undershirt (for example, if it is worn with a sleeveless jersey), except that pitchers may not have such devices on their undershirt sleeves.
• The league office might require that each team have a single uniform for all games or requires that each team have a single, white home uniform and a single, non-white away uniform. With the elimination of the separate American League and National League administrations, it is unknown what the effectiveness of this rule now is.
• Sleeve length: The rules allow for minor variation in sleeve length, but they must be "approximately the same length" and the sleeves may not be "ragged, frayed or slit."
• No attachments: Tape or other attachments of non-matching color may not be used on uniforms. Pants may not be attached to the bottom of the shoe in any manner.
• No images of baseballs: No "pattern that imitates or suggests the shape of a baseball" may be used on uniforms. Notably, in apparent violation of this rule, the Toronto Blue Jays, Milwaukee Brewers, Los Angeles Angels of Anaheim, Miami Marlins and Philadelphia Phillies for many years had logos that incorporated the image of a baseball. However, while the Philadelphia cap logo clearly depicted the baseball, the logo worn on the uniform jersey did not feature the image of the stylized stitching indicating the image of a baseball. The former Florida Marlins logo, while depicting a baseball, could not easily be mistaken for one, as the team's namesake fish is displayed in front of the ball design. The Marlins adopted a new logo—without a baseball image—when they adopted the new name of Miami Marlins in advance of the 2012 opening of their new park. The Toronto Blue Jays had a similar design with a Blue Jay head on the front of the ball, and this logo was even used on the center (and later left-center) of the uniform itself. The classic Brewers "ball and glove" logo (with the team's initials, MB, stylized into the shape of a blue baseball glove surrounding a ball) made a comeback in 2006 on the hats of the Brewers' Sunday home uniforms and is now the Brewers' Friday home uniform. Also, many teams such as the Giants, Nationals, Rangers and the Mariners use uniform logos that clearly depict a baseball, the New York Mets have featured uniforms with a sleeve logo that imitates the appearance of a baseball since the team's inception in 1962, so it may be that the rule is not enforced, at least for caps. (The purpose of this rule is to prevent one team from deceiving the other. The National Football League has a similar rule, which states that no pattern that imitates or suggests the shape of a football).
• No glass buttons or polished metal.
• No commercial advertisements on uniforms. This rule is at variance with many other professional sports. In North America, corporate sponsors' logos are ubiquitous on vehicles and uniforms in motorsports (such as NASCAR, IndyCar, and the NHRA). Outside of motorsports, sponsor logos are increasingly common in leagues such as the Arena Football League, WNBA, and soccer leagues such as MLS and WPS. Corporate logos on uniforms are even more widespread outside North America, most notably in soccer. The commemorative patches worn by the New York Mets during their inaugural season at the Citigroup sponsored Citi Field did not feature the name of the ballpark in adherence to this rule. However, when the New York Yankees and Tampa Bay Devil Rays opened the season in Japan in 2004, an ad for Ricoh was clearly visible on the batters' helmets. When the Oakland Athletics and Boston Red Sox opened the 2008 season in Tokyo, not only did both teams wear batting helmets featuring the Ricoh ad; but also, the Red Sox featured a commercial advertisement for a New England-based business on their jerseys and the A's jerseys featured an advertisement for Pepsi. Exceptions are made for the manufacturers of the pieces of uniform or equipment upon which they are placed (i.e. the hat manufacturer's emblem may be on the hat).
• Names: "A league may provide that the uniforms of its member teams include the names of its players on their backs. Any name other than the last name of the player must be approved by the League President. If adopted, all uniforms for a team must have the names of its players." Again, with the elimination of separate administrations for the American and National leagues, it is unknown what the provenance of this rule is. (Ichiro Suzuki, when he played for the Seattle Mariners, is the last player to have his given name rather than his family name displayed on the back of his uniform, having applied for this permission in order to continue being identified as he had been in the Japanese leagues. Vida Blue also used his first name on the back of his uniform when he played for the San Francisco Giants in the mid-1980s). As of 2010, the New York Yankees, Boston Red Sox and San Francisco Giants do not display their players' names on their home uniforms (the Giants did adopt the names in the 1970s, but removed them from the home uniform in 2000); the Yankees also do not display them on their road uniforms. The New York Mets used alternate home uniforms without last names for the 1999 season. The names were returned the next season. The Chicago Cubs did not have names on their home or alternate jerseys for the 2005 and 2006 seasons. The names are now back on both jerseys. The Los Angeles Dodgers did not have names on the back of their home and road jerseys for the 2005 and 2006 seasons. Names returned on both jerseys in 2007. The Minnesota Twins did not feature names on the back of three different "throwback" alternate uniforms, used in 2009, 2010 and 2011. The practice of removing names from Jerseys is believed by many to be a direct result of lagging program sales.

After the death of Twins great Harmon Killebrew in May 2011, the Twins' 2011 "throwback" alternate uniform became the primary home uniform in honor of Killebrew, who wore a similar style of uniform during his playing days with the Twins.

Another apparent violation of the concept of a "uniform" is that some players on a team will wear the traditional knee-breeches or "knickers" while other teammates are wearing the more-recent ankle-length, closely cut trousers. Many clubs do this at both major and minor league level, with no apparent objections.

On game days that do not require a special uniform (either by team or MLB request) it is generally (but not always) the starting pitcher for a team that chooses the uniform to be worn for that day's game.