Were these programmers magically transformed from "Bad programmers" to "Good programmers" overnight?

Er... no, they're still the bad programmers. Bad programmers can write good code. They just require much, much more handholding. And a project manager can't do that handholding; it has to be a good programmer. (Note that a great project manager can fill in that role -- if he happens to be a good programmer.)

I'm not saying project management is useless. In fact, it's critical. But I fully agree with the original quote -- it's not enough by itself, and much, much less of it is needed if you have good programmers in the first place. Which isn't saying much, because part of what makes a programmer good is being able to do a part of the project management.

It is certainly possible to create a decent product with a team of bad programmers and a good project manager. I've seen it done. And I've seen two good programmers get fed up with the pointless lack of flexibility and maintainability, and rewrite the whole thing in less time and produce a far better product. Admittedly, they gained from the experience of the first implementation, but they didn't stop there -- by the time they finished, the product had at least twice the functionality of the original (it was being sold in parallel, so new requirements were pouring in.) And it was still easier to maintain and extend, and there still wasn't a product manager involved. Sure, it's anecdotal, and there were some near-disasters that could have been avoided with better project management, but it still supports the original claim.