1. How experienced were these people in the particular problem domain?
2. How long was a single development effort and how many people?
3. What do you consider Waterfall? Are we talking "pure" Waterfall where everything is truly done in set phases? Or do you have feedback loops in place, like testing integrated properly into the development phase?
4. What was the relationships like with customers? Was it one (or a small number) of consistent customers or a diverse set of customers (closer to contract/bespoke software work)?