Immediately following his rookie season, Zimmer played winter ball in Puerto Rico, emerging as a decidedly dark horse 1955 Caribbean Series MVP on the heavy-hitting 1954–1955 Cangrejeros de Santurce club managed by Herman Franks. Nicknamed El Escuadrón del Pánico (lit. "The Panic Squad"), the team featured future Hall-of-Famers Willie Mays and Roberto Clemente, future All-Stars George Crowe and Sam Jones, local hero Luis Olmo, as well as Negro leagues stars Bob Thurman and Buster Clarkson. It was later described by Zimmer as "probably the best winter league baseball club ever assembled."