58? When? (The over under for Nate Silver for the Senate was 51 seats in 2014. That being the case, then 54 seats after this election was over performing, much to my surprise.)
58% to 42% in favor of Cassidy.
Here's the thread:
Senate Forecast: Landrieu Headed Toward Historic Defeat In Louisiana Runoff (Nate Silver)
As you note, Nate didn't do too well with his overall Senate prediction in November. He wrote an interesting post-election analysis where he said there was something out there that he and the other pollsters were missing in off-year elections in general, and that he was going to to focus on finding out what it was.