Original: Soon after the band was formed, Dee Dee realized that he could not sing and play his bass guitar simultaneously; with Erdelyi's encouragement, Joey became the band's new lead singer. Dee Dee would continue, however, to count off each song's tempo with his signature rapid-fire shout of "1-2-3-4!"
Simplified: Then Dee Dee said he was unable to sing while playing bass so Tommy got Joey to sing and then played drums himself leaving Dee Dee to backup sing.