Chait nails it:
Not having listened to Kerry speak since the primaries, I was surprised how awful and meandering his speech was. Even worse, it was politically tone-deaf. When discussing America’s role in the world, he put the emphasis on restoring alliances rather than keeping America safe and strong. He’s inviting the Republicans to translate his remarks into, “He won’t go to war without permission from France.” He also had a riff about investing in education rather than spending the money on prisons. That sounded very much like a belief that prisons come at the expense of education. (In truth, criminals prey mainly on the poor. Keeping criminals off the streets allows poor kids the safety they need to have some chance at getting ahead.) Substance aside, I think Clinton showed pretty clearly that the right political message for Democrats is to be tough on crime. What made Kerry’s departure from the Clinton pattern all the more striking is that there was nothing about prisons in the prepared text. It was all ad-libbed. Talk about bad instincts.
Right now, the profound weakness of Kerry’s candidacy – the man himself – has been obscured. Edwards is a perfect way both to keep it that way and to sell the positive aspects of the idea of a Kerry presidency (rather than the tedious, uninspiring reality). Again: a very smart pick.