For a man of the street, accomplished at dealing on the street, Key seemed flat-footed.
But there were other opportunities he missed. When Goff spoke of the nobility and wisdom of removing GST on fresh fruit and vegetables, he needed to be reminded that for more than 20 years he was one of the Labour group who said it wouldn't work and would be too confusing.
When, as late as July this year, Labour were on the record as being opposed to any raising of the age of retirement, and when David Parker admitted on Q&A on Sunday morning that the movement of the superannuation age to 67 had been decided only a fortnight before, Key could have suggested the politics of desperation.
Key was relying on being Key. It may be hindsight, but I think once his people had absorbed that first massive punch from Labour that seized the political agenda, namely the movement of the retirement age, they should have known Goff might well come out scrapping. And in those first few minutes he was landing some good blows.
I thought Guyon Espiner did a good job. He let the two leaders go, he let them engage on an issue. Trouble with that is, it is hard to pull them back to change subject or go to a commercial break, or to change direction.
Moderating leaders' political debates on television in election campaigns is ferociously difficult. I know. I've done enough of them. You never please everyone.
And, as I've said before, political leaders trying to will their parties to power on televised debates during election campaigns have a fierce momentum.
Their ambition is raw, almost palpable. And trying to stop them or steer them on a new course is like standing in front of a freight train.
In the end, I wonder about the effect that the TV debates have on the final vote.
If you don't like someone for a year or more, you aren't going to change your mind and vote for that person because they might be technically the stronger debater.
You could make the case that Goff was the stronger debater last Monday night. But did you notice the most telling result of the texts to the programme at the end of the debate? According to the texters, Key had won it handsomely.
But TV is wonderfully honest - and wonderfully treacherous.
Sometimes, it's all in the little things. Goff might have apparently struck a blow by calling Key a liar.
But we all know all politicians tell the odd fib or withhold information, and we all know they have to make the decisions demanded when circumstances change.
For example, the GST.
But Key is still able to project the image of an honest, ordinary guy. And I think that is still what the market wants. I seem to remember that at one point he stood there with one hand in a trouser pocket, projecting a man at ease in his job.
And when called a liar, his reply that he would not call Goff a liar because he had too much respect for the office of leader of the Opposition was simply dignified.
By Wednesday, Key was in ruthless fighting form. Show me the numbers, he goaded Goff in Christchurch. And, unbelievably, Goff didn't have them. Breakthrough.
And despite the perceived brilliance of Labour's blitzkrieg superannuation strategy, the Colmar Brunton poll showed that the idea had done nothing at all for Labour. The gap between the two major parties only widened. Labour support dropped into the 20s.
The Labour people must have torn their hair out when they saw the numbers.
In the end, it may be all about who you like. And right now the country likes Key. By a country mile.
As for Key apparently being boxed in on his adherence to 65 as the age for superannuation, well, no politician of calibre is ever boxed in for long. Everyone knows that the age of superannuation will have to be moved up to 67 one day. We know we don't have to worry about it just yet, and we're not in the mood to discuss it right now. And I have the feeling that nor are we in any mood for clumsy and complicated taxes like capital gains. As far as most people are concerned, any little bit of capital gain you can make at the moment, well, good on you.
