High Quality Content by WIKIPEDIA articles! Thomas Francis "Tom" Hallion (born September 5, 1956) is an American umpire in Major League Baseball who has worked in the National League from 1985 to 1999 and throughout both major leagues since 2005. He is currently a crew chief. Hallion is well known for his exciting and demonstrative strikeout signal in which he twists his body 180 degrees. He was among the umpires who lost their jobs after resigning as part of a failed union bargaining strategy in 1999, but his rehiring was agreed to in December 2004 in a settlement with Major League Baseball. Hallion wore uniform number 20 during his National League career and retained the number when he rejoined the MLB umpire staff in 2005.