Same pitch, same XI; just what clicked for South Africa?

If a definition of insanity is to ask the same question and expect a different answer, South Africa went mad in Grenada on Sunday. What did they think they were doing, having been smashed by eight wickets with five overs to spare in the first T20I on Saturday - not only at the same ground but on the same pitch - sending an unchanged XI into the fray?

It seemed an odd decision that yielded an inexplicable result: South Africa won