This is an underwhelming performance for Sanders if true. Frankly I don't understand why the Clinton campaign doesn't contest the state more aggressively, a win in Wisconsin will completely discredit Sanders as a serious candidate, at least in the eyes of the media.
Well the harder that try the bigger deal it is if they lose. Sanders it out spending them significantly and has 3 events in WI today alone. Clinton has no more events in WI before the primary. If it is close they can spin it as a win.
I think they are looking more at NY and PA to be the knockout. Sanders has to win at least one to prove he is viable.
Losing SC by nearly 50 points was supposed to discredit him in the eyes of the media. Then losing MA was supposed to. Then losing every March 15th state was supposed to. They're clearly not going to give up on the horse race narrative, and Bernie has no intention of dropping out until the final votes are cast. That's fine for him, he's well within his rights to do so, but that's why Hillary is only putting in a token effort. A narrow win for her there would change things as much as her narrow win in MA did (i.e. not at all.)