A game shouldn't be won/lost in last over. Too many ifs, buts and shouldves. Like Picard said short pitched bowling in the start allowed McCallum to set the perfect tone. It was just a matter of keeping the rate from there. There was never pressure.
When a bit time bowler like AB comes on to bowl in a semi final of a WC something is bloody wrong.
I agree that it shouldn't have gone anywhere close to the last over. IMHO, AB had a shocking game as captain. McCullum had just as bad a game with his captaincy only to get saved a bit on that front by the rain.
Here are some of the things that I think AB did wrong:
1) He put the wrong bowlers in at the wrong time. e.g. He should have bowled Steyn when Duminy first came on. New batsmen, attack and get them on the back foot after their good start. Also, why on earth did he wait until the 6th over to bring on Tahir with the carnage that was going on?
2) Field placings were bad. NZ got far too many boundaries in the middle overs. The rate was never given a chance to climb. Go back and look at how many good overs were ruined by a four in the last 2 balls. That often happened because he kept attacking. After 4 balls of attacking, if you have 4 dot balls, drop a couple more fielder back and give them a couple of singles. It's an instant rate increase. At one point their was an Indian commentator was beside himself saying that SA were throwing runs away.
3) Emotion. AB gets too emotional. When the crunch time hits, you need a captain that looks completely calm on the surface. He should be a beacon for the other players. AB looked almost desperate at times with his fielding.
4) Why on earth did he keep persisting with Duminy for so long. He should have brought himself in for an over much earlier. After the first time Duminy got wayward (wides, leg side balls, etc). Instead, he kept bringing Duminy back over and over and the times when he did it the pressure release was noticeable.
5) Reviewing Tahir's LBW. Again? It didn't cost anything but it could have been massive.
It's funny because he was almost perfect in the SL game. It was the first game that I think he captained like a captain. If you look back at someone like Stephen Flemming. He never had many good players but he could pull rabbits out of a hat with those players. SA have 2 of the top 3 ODI batsmen in the world and 5 of the top 28. They have 3 of the top 10 bowlers in the world, including no's 2 and 5.They are, on paper, probably the best side in the tournament. Can you imagine what someone like Flemming would have done with this side?
SA didn't choke. Things could easily have gone the other way. The dropped catch in the second last over and people might just be saying that NZ choked. The problem was that it should just never have been that tight at the end. NZ did amazingly well to chase down the big total. It just feels to me like SA let them.
SA have this habit of not looking at conditions. Leaving the big run chase to the last 20 overs is all fine and well but you need to look at the weather to see if it's a good idea first.