sˈaɪnd æz ɐn ˈæmətʃɚ fɹˈiː ˈeɪdʒənt baɪ ðə pˈɪtsbɜːɡ pˈaɪɹəts ɪn nˈaɪntiːnhˈʌndɹɪd fˈoːɹɾi, kˈɑːks mˌeɪd hɪz ˌɛmˌɛlbˈiː deɪbjˈuː wɪððə pˈaɪɹəts ˌɔn sɛptˈɛmbɚ twˈɛnti, nˈaɪntiːnhˈʌndɹɪd fˈoːɹɾi wˈʌn, plˈeɪɪŋ ɪn tˈɛn ɡˈeɪmz æt ʃˈɔːɹtstɑːp ðæt sˈiːzən bᵻfˌoːɹ sˈɜːvɪŋ ɪnðə mˈɪlətˌɛɹi dˈʊɹɹɪŋ wˈɜːld wˈɔːɹ ɹˌoʊmən tˈuː.
Signed as an amateur free agent by the Pittsburgh Pirates in 1940, Cox made his MLB debut with the Pirates on September 20, 1941, playing in ten games at shortstop that season before serving in the military during World War II.