Personally, IMHO, I think Firpo's style is just crazy enough to give Ruiz some problems. And Firpo could take a pretty good punch. Actually, Luis might even knock Andy down once, but the reverse is also true. I'm going with Ruiz by Decision, but I wouldn't bet the farm on it.
I'd bet the farm on Ruiz winning, probably by some sort of stoppage as he picks Firpo apart and overwhelms him with his surprising skills and handspeed. Wouldn't be competitive, IMO.
Give this one to the "new school" fighter. Firpo with what little film we have of him, was usually off balance, also telegraphed his punches. Ruiz's is a well schooled fighter, though portly , he is surprisingly quick fisted. This fight in all likelihood is a blow out. Ruiz by early ko.