Let me make sure I understand: this is the first time, in all of MLB history, that a game was won with someone other than a pitcher functioning as the pitcher? I'm really surprised if that hadn't ever happened before...

Not just won, but went from either a negative or neutral position to win.

IE. if it's happened before, the team was already ahead when the non-pitcher took over in relief.

@moonsammy No, it's not the first time a non pitcher was on the mound when there team won. It's the first time a non pitcher was credited with a pitching "Save". His team had a two run lead when he entered the game as a pitcher. The previous pitcher was awarded the "Win".
http://m.mlb.com/glossary/standard-stats/save

There are plenty of position players who have recorded a win as a pitcher. You can find them among this list. https://www.baseball-reference.com/friv/fieldPitch.shtml

(edit) As a side note, first time since 1969 when the save stat was made official.

One gets the feeling he won't be a center fielder for much longer.

That's why it's called The USA's National Pass-out...er... I mean Pastime. I jest, I jest!

But hey, I spent my two-minute in this video looking for rats... and I failed to see any... how can this be?!