To put Hiura's K numbers in perspective he has a worse K% than Russel Branyan, Jose Hernandez and Chris Carter. There is a reason why Hiura has been bad and it is because of his K%. Also he has hole in his swing that covers the whole top third of the strike zone that pitchers can take advantage of and it is not just fastballs that he misses up there it is everything in the upper third of the strike zone. His swing just doesn't allow him to get on top of or on balls placed in the upper third of the strike zone. If a pitcher just throws pitches in the upper third of the strike zone they can get Hiura out and they can easily K him there. Nearly all of his strike outs have come at the upper third of the strike zone and a vast majority of his whiffs come from there also.
Hiura is just not a good hitter. He may have hot streaks from time to time but his cold streaks are far more common.