Side judge Keith Washington took the number upon Blum 's retirement .
He was the first non-referee to wear the uniform number 7 ; the number belonged to long - time referees Tommy Bell and Fred Silva before Blum assumed it upon his promotion to crew chief .
Side judge Keith Washington took the number upon Blum 's retirement .
He was the first non-referee to wear the uniform number 7 ; the number belonged to long - time referees Tommy Bell and Fred Silva before Blum assumed it upon his promotion to crew chief .