Eh, that's not necessarily true. Anybody with any sense could have told you this was coming literally years in advance.
The Senate seats that are up for election in this year's midterms are the same seats that were up for election in Obama's first presidential election year. That was a Democratic wave election where virtually every race that could have broken one way or another broke for the Democrats, thanks to Obama leading people to the polls. These included many normally red Senate seats that uncharacteristically flipped blue. These were always going to go right back to being red when they came back up for reelection in 2014 due to a return to a more "typical" election environment. There is no generational candidate leading the charge at the top of the ballot to lift up those Senate candidates, and the demographics of a midterm election favor Republicans to begin with. This is basically a return to the status quo for many of these seats, with the Democratic incumbent sitting in them now the actual outlier.
Simply put, for Republicans to fail to take back the Senate, something would have to be really really really wrong with them.
