13

From BR Bullpen

Number 13 has traditionally been shunned by players because of traditional superstitious beliefs associated with the number in western culture. The fact that Ralph Branca wore it when he gave up the Shot Heard 'Round the World also contributed to its unpopularity within baseball circles. However, it is popular in Venezuela, which explains why Dave Concepcion, Omar Vizquel and Edgardo Alfonzo have all worn it. Since the 1970s, the number has been worn much more frequently.