I don't think they looked his numbers at all. I think somebody in the front office wanted him really bad (like Theo Epstein going ballistic over losing Jose Contreras to NYY) and the Dodgers played into the Braves' desire. Maybe it was the Cuban connection with Fredi, maybe it was the showcase, who knows the genesis of it.
Taking a gamble on Olivera would have made a lot of sense for a lot of teams. Despite the fact that his elbow was a major question mark and there were still lingering questions about his skill level and long-term position. But not for the Braves and not for Peraza and Wood, even more certainly. No matter how hard you try to bury those two pieces, they were still valuable players at the time and, sure, they're perhaps less valuable now - but they are still actually playing Major League baseball, and will likely continue to do so for the foreseeable future.