I agree with Schmoeman. Wallner speedy and aggressive coming in on balls, very shaky going back, especially in RF at Target, as he clearly is cautious about the wall and rebounds off the structures. The game where Keuchel carried the no hitter into the 7th, the first hit surrendered was a ball up against the padded area of Right Center that Kepler might have caught.
Wallner had no chance at it, he started back, gave up, and then tried to play the bounce.