I had that same reaction- I had heard his VA for the DLC in Lost Judgment and it didn't bother me at all. It fit the character (even at the end when he hulks up for the boss fight) fine and it also sounded, to my untrained ear at least, that Yong was putting a decent amount of effort into it. His anime work seems alright too. But man, that Kiryu, no bueno.
I looked up some of Yong's other VA worked after hearing this nightmare and most of it is sounded fine to me.
This is just a horribly bad casting choice that absolutely ruins Kiryu, but as others have said that playing these games in English is a weird-ass choice to begin with.