His K rate is higher than normal. Today is the perfect example of him lowering his K rate, lowering his BABIP, but raising his OPS.
Also, he doesn't need to compare to the majority of players, because the majority doesn't have his bat speed. He's going to continue to do uncommon things, because he is uncommon. Someone might have an incredibly high BAPIP this year, right? It is, I know because Hiura has done it before.
Also, you continue to use the word "regress", but I think it's more applicable to use the word "decline". A player can have positive regression. In fact, that's what Hiura is doing this year.