Rather than New Zealand batting getting better, it was actually the South African bowling getting worse. And poor captaincy tactics and misfields didn't help the cause either. Among the Protean bowlers, only Nqobani Mokoena had an economy of less than 6. Keshav Maharaj went for 15 runs per over (why this guy is not getting dropped?), while George Linde went for 33 in his three overs.
South Africa had bowled out New Zealand for 91 runs in the first T20 match, and today New Zealand bowled out South Africa for 107 runs in the second match. That is, New Zealand avenged South Africa's defeat in the first match in the second match.
Two matches in the five-match T20 series have already been tied, meaning we will see more intense competition between the two teams in the remaining three matches. However, we cannot yet guarantee that either South Africa or New Zealand will win the series.