We don't even need to add them up. We can just look at them individually.
There are three areas to evaluate a position player in baseball: Hitting, Fielding, Baserunning.
Cabrera beats Trout in hitting, and it's not close. (73.0 to 60.1)
Trout beats Cabrera in base running, and it's not close. (8.1 to -4.3)
Trout beats Cabrera in the field, and it really isn't close. (4.0 to -15.4)
These are all sensible arguments that don't even need a number to defend. Is anyone in their right mind going to argue Trout's a better hitter, Cabrera's a better base runner, or Cabrera's better in the field?
I love this article. It sums the Trout vs Cabrera thing up very very well.
http://www.baseballnation.com/2012/11/16/3654460/mike-trout-miguel-cabrera-stats-mvp