First off for the record this poll is two months old, not sure why it was posted now.
Second Minnesota has been trending Democratic across the board. No Republican has won a statewide race since 2006 (Tim Pawlenty). No Republican has gotten 50%+ of the vote statewide since 1996 (Arne Carlson). The rural republican areas of the state are shedding population while the liberal Twin Cities have been booming. Unless there is a Republican landslide nationally Minnesota is safe Democrat for the presidency in 2016.
Okay it is NOT trending Democrat. Lol. PS everyone, Minnesota democrats are typically moderate and fairly conservative on social issues. I see no reason why it is implausible for them to begin voting republican when democrats are increasingly liberal and are isolating white voters.
On what issues are Democrats "increasingly liberal" than the same general policies they've run on--and consistently carried Minnesota-- during the last 30-40 years? Voting for dovish, pro-choice, pro-union, economically and socially liberal Democrats is hardly new to Minnesotans. The one exception from past-decades may be Democrats now being solidly pro-gay marriage, which is a popular issue nationally and even more so in MN.
There are other issues at work here that hurt MN Democrats to be sure, but your "analysis" misses them entirely.