If you've learned anything about WI, always add 2-3 points to the Democrats' final polling numbers. They ALWAYS close well, usually due to Same Day Reg. In 2004, this is what nipped Bush there. In 2010, it ALMOST got Feingold back in office and trimmed Walker's victory.
Except when they don't?
2010 is no longer a valid analogy for 2014. Democrats did not see what hit them in 2010. In 2014 the Tea Party nominees are nothing new.
Walker has his base solid, and any Democratic win of Wisconsin in 2014 or 2016 will depend upon Democrats getting the vote out. The GOP base is not enough for winning statewide elections in Wisconsin as is so in Kansas.