I've worked in ruby, python, java, and most recently, scala -- on both small and large projects. Tangled hairballs and hidden runtime exceptions can happen anywhere. I've just seen less of it with Java. I think this is partly because the compiler catches things that one would need to write tests to catch in ruby. For me the compiler is another layer of defense keeping bad code out of production.

Another advantage of statically typed OOP code for big teams is it allows a verbose yet formal way to define interfaces as a team, and then break up the work into smaller chunks. The formality can certainly slow an individual programmer down, but in a big team I've found it makes breaking up the work easier.

I wouldn't argue against the notion that ruby's expressiveness and use of functional paradigms might make up for it's lack of static typing, and ruby in the hands of a great programmer is pure pleasure, but most teams don't have just great programmers.

Finally, I absolutely love Scala and I think it's worth mentioning in any discussion of ruby and java. It, sorta, bridges the gap between the two languages and I'd recommend it as a good choice for a team of any size.