I'd agree with you if it weren't for the fact that the "from scratch" part of this problem includes the fact that the (hi! welcome to the club!) new developer (here's your new hat!) is woefully unprepared to know what the issues/problems are and where to find solutions that fit them. Of course, I have that problem too and I've been doing this for years.

In any case, I don't think it's an answerable question short of seeing the code itself and ideally the functional specs for what the code is apparently solving. Figuring out legacy code can do wonders for jumpstarting your knowledge base (it's how I got started) and limits the feeling of helplessness that can hammer you if you have no experience in handling this sort of situation.

This may not fit the goals of the original poster, but you might consider hiring another consultant. And checking if they have a handle here for good measure ;). Hell, even if the company won't go for it, it might be worth paying some amount of your own personal money to get a little hand-holding as you work through it. Or just abuse the hell out of SoPW for the cheap, yet amazingly effective method!