The question this really begs is....why did Bush get so few electoral votes in 2004 relative to his three million vote win in the popular vote? Just looking at the states that were closest doesn't help a whole lot...
Bush did very well in Republican states in 2004 and among many different voting groups, while Kerry did worse in many Democratic states compared to Obama and Clinton. Trump performed worse in several Bush states and barely won many of the states that catapulted him to a wide electoral college victory, resulting in a wide PV/EV disparity. Pennsylvania, Michigan, and Wisconsin are still Democratic states, it's just that Democrats didn't vote like they did in previous elections, allowing Trump to win despite only modestly overperforming Romney.
They are GOP states every off year election and are probably tossups (maybe lean dem) in presidential years.
