Let's go back a bit further. If you look at Indiana's election results from 1980 onwards, you will notice that:
-If the national result is a Republican victory or a close Democratic victory, the result in Indiana is a Republican blowout.
-If the national result is a Democratic blowout, Indiana is competitive.
In both 1992 and 1996, Bill Clinton came within 7% of winning Indiana, while Obama won it outright in 2008 (he was projected by most outlets to lose it narrowly).
You combine this paradigm with two other factors: Obama being from Illinois and the impacts of the recession, it opened the door to IN going Dem.
Another factor was McCain's campaign presumed a lot of things about the map, including that Indiana would go Republican because it had not voted Dem since 1964 and because of Mitch Daniels expected landslide (which did happen), both of which were wishful thinking as it relates to the Presidential results.
