Current polling isn't adding up. I could see WI being slightly more Democratic than MI, but there's no way that WI is Safe D, while MI is a Toss-Up (If you buy all of the polls, you have to believe that IA is Likely R, as well.) I doubt that Republicans will come super close to winning WI, but if Democrats are up by this much, they should be doing at least as well as Obama '12 in most other states.
Iowa and Wisconsin usually vote together. The last exception involved both states being so close to the margin that they were practically identical. Michigan is basically Wisconsin with more blacks. Of course, neither Iowa nor Michigan has so unpopular an incumbent Republican governor as Scott Walker.
Because of the early caucuses in Iowa, and because until recently Republicans have gotten more attention, Republicans dominate the political discussion in Iowa. Sure, the state voted for Joni Ernst for the Senate last year -- but she is terribly unpopular.
Polls after the Iowa caucuses will not show the current Republican advantage of constant attention. They will likely either show Iowa going back to its norm or a genuine Republican shift in the states politics.