As with the Jason Bay projection, we were wrong here but still did better than ZiPS. (PECOTA actually deserves a gold star here for actually being more optimistic than we were, pegging Nady at .278/.334/.460, although I believe the actual Baseball Prospectus book wasn't nearly so positive.)
Leading the charge off a cliff were myself and Pat, as we were both really virulently anti-Nady last offseason. Fortunately, the Pirates didn't listen to us, and the Bucs managed to make a rare trade where a bad team managed to actually get something for a nearing-30 never-has-been like Nady.
I look for something I can learn from this, but I'm not sure there is anything. Lost in... whatever the Pirates and Yankees were doing in August and September is the fact that Nady went right back to being his usual mediocre self once the Pirates dealt him. He slammed a bunch of homers shortly after the trade but flamed out badly in September, and he ended up posting a .268/.320/.474 line with New York. That isn't horrible, but it couldn't have been what the Yankees were hoping for, and Nady's 108 OPS+ with the Yanks compares closely to his 107 with the Pirates in 2007, as well as his 102 in 2006 and his 104 in 2005.
But for four glorious months with the Pirates, Nady's been a very consistent player. Expect more consistency next year. And, if he's lucky, the year after that, by which point we're hopefully going to be very glad we've got Jose Tabata. The Pirates' front office did a great job handling Nady, and I'm glad I was wrong, but I'll always suspect they just got really lucky.
Geosport had the best prediction, guessing that Nady would hit .301/.355/.496.