I think playing Ortiz at first is the right thing to do
Wilner (Ug) said it well the other day - "You can't lose the World Series with David Ortiz sitting on the bench"
I agree. He's your age-defying playoff hitting legend. And it's first base. And he's not exactly replacing a gold glover.
A tougher decision would be playing Napoli at third. THAT could have consequences but he's apparently thinking about it