It was rewrite "from scratch" (not refactoring), but with the previous team available to answer any question (either about the legacy code or the domain, which

It was rewrite "from scratch" (not refactoring), but with the previous team available to answer any question (either about the legacy code or the domain, which they knew well), which was an essential part of the success (I guess a lot of rewrite fail because they are done by new people that didn't take care to learn enough from the old system and the domain to thoroughly understand what must be done). The legacy code was too bad to make refactoring worth it, but surely not every legacy system is in that bad of a shape.