Donaldson really fell into a bit of a slump towards the end of the season.
He had that walkoff in the last home game, but he actually lost the edge in fWAR in the last week or so. He was up by 0.1 (I think around the time the Jays went on the last road trip) and Trout finished 0.4 ahead.
Unfortunately, I wouldn't be shocked if Trout stole it to be honest. He's leading offensively in all the traditional stats. Same number of HRs but in 29 less plate appearances, higher walk rate, quite a bit higher ISO (19 points), quite a bit higher OBP (31 points) and SLG (22 points). Donaldson has more RBIs and Rs, but those are also team dependent stats, it's not Trout's fault if there's nobody on base for him to drive in, or if nobody is knocking him in. Trout leads in wOBA and especially wRC+ by a pretty big margin too.
I honestly don't know if those with a vote have even gravitated towards saber stats yet, but Trout has the edge in pretty much all the traditional or advanced stats. The only team independent offensive stat Donaldson leads in, is that he struck out about 5% less of the time, and he was better defensively. Then there's the subjective argument that Donaldson's team made the playoffs and Trout's didn't -- which you can't say is only Trout's fault.
It will be close, but like I said, I won't be shocked if Trout stole it. I'd actually be pretty surprised if Donaldson won it since Trout edges him out nearly everywhere.