WI has a GOP governor and control of both state houses. Walker has had to not only win election, but to survive recall efforts. Has to account for something with regard to GOP strength in a statewide race, which Trump/Clinton is.
Not really. All of Walker's elections were in non-presidential years. For presidential elections the turnout averages over 700,000 votes higher than in non-presidential elections. Wisconsin has gone Democrat in every election since 1984 I believe.
Add to that the fact that Trump lost the Wisconsin primary, that he's polling poorly in the state, and his feud with Ryan and it all adds up to there being much easier states for Trump to take than Wisconsin.