Hiura hasn't really made any adjustments to his swing. He is about the same as he was in 2021 with balls in the upper part of the strike zone. Hiura basically can not hit in the upper part of the strike zone as the majority of his hits come from either middle-middle, middle-away, low-inside or low-middle. Hiura has exactly one hit in the upper part of the strike zone and that is up-away which was a single.
Hiura basically has zero power and about a zero percent chance of getting a hit in the upper part of the strike zone as he whiff's at those pitches more than he does in any other spot of the strike zone. Even going all the way back to 2019 Hiura has had trouble with pitches in the upper part of the strike zone. But in 2019 he was able to get a few more hits and he wasn't whiffing at the same rate as he has been since 2021.
His current season looks exactly like 2019 and 2021 in the mid to lower part of the strike zone. I don't believe there has been any improvement in Hiura at all he is still the same player he has been. Teams are still going to exploit the top of the strike zone against Hiura and even if Hiura watches the pitches go by they are still strikes. The issue with Hiura is that he can only hit in the middle to lower part of the strike zone. Hiura has a very low chance of getting a hit in the top portion of the strike zone. When teams start making the adjustment back to the upper part of the strike zone Hiura is absolutely useless as he can't hit in the upper part of the strike zone at all.