Smoak is very head ups on the defensive side of the ball. There was a play the other day that was a bang bang decision on a bunt and he made a very nice judgement call to let it go foul. These plays won't get measured.
There are just a handful of defenders that are better then Smoak in the league. Teix, Loney, maybe Hosmer? Point being his defense alone is worth putting in there for Bello, let alone there very similar hitters.