Helen Zille's social-media-driven campaign has successfully convinced Johannesburg voters the city is broken and the ANC has lost their trust – polling puts the DA near 40%, the ANC in the low-20s. But as Hermann Pretorius writes in this piece for The Daily Friend, analyst Gareth van Onselen's research shows the real battle now is turnout, not diagnosis: the DA needs roughly 500,000 votes to break 50%, in a city where turnout has collapsed and s…