I think at this point we have enough sample size and tape that we can conclude that Trout's defense is/was overrated. Not saying he's a slouch, but his value doesn't really come from his defense. It's his bat and speed.
Donaldson though is pure magic at 3B though. With Machado gone down he's probably the defensive class of the AL.
In the end this is irrelevant though unfortunately. Voters don't really care about defense in the MVP voting.
I'm guessing it's from the bulk he's added over the last year or so?