Who should have stood: Alastair Darling, he is a much more substantive figure than any of the candidates. The economic woes were largely the result of his predecessor as Chancellor and he appears to be an honourable individual (resisted pressure from Brown & Balls to cook the books according to Mandleson's memoirs) apart from a bit of flipping.
Now, as well as his existing strengths he would be able to portray himself as the saviour of the Union. I suspect that if he were the Labour leader they'd currently be heading for government. Labour supporters must be pulling their hair out when they see how effective Darling can be compared to Ed Miliband.