<P> The tradition in the Major League Baseball mascot began with Mr. Met, introduced for the New York Mets when Shea Stadium opened in 1964 . Although some mascots came and went over time, the popularity of mascots increased when The San Diego Chicken started independently making appearances at San Diego Padres games in 1977 . Philadelphia Phillies management felt they needed a mascot similar to the Chicken, so they debuted the Phillie Phanatic in 1978 . </P> <P> Today, all but three major - league teams have "official" mascots (Dodgers, Yankees, and Angels). Five team mascots--Sluggerrr (Kansas City Royals), the San Diego Chicken, the Phillie Phanatic, Mr. Met, and Slider (Cleveland Indians)--have been inducted into the Mascot Hall of Fame . Several others have been nominated since the Hall's creation in 2005 . </P> <P> Ace is the official mascot of the Toronto Blue Jays . He, along with his female counterpart, "Diamond" replaced former mascot BJ Birdie before the 2002 season as a mascot duo . Like his predecessor, Ace resembles a large blue jay . The mascot's name is baseball slang for a team's top starting pitcher (the "ace" of the staff, such as former Blue Jays pitcher Roy Halladay). </P> <P> In 2004, Ace became the sole mascot of the team after Diamond was removed by the Blue Jays prior to the start of the season . In 2011, Blue Jays fans were introduced to his younger brother Junior (see below). </P>

Old baseball mascot with a c on his cap