Not saying that Kenta is pitching well or isn't of concern, because he is, but this isn't that uncommon of an outcome even for winning teams in this sport. The Cubs (likely an above .500 baseball team) lost a game 12-11 this week; the Yankees lost to the Guardians on Sunday 10-7, etc. And the Texas Rangers, even with their injuries, are still a really good offensive baseball team.... they are hard to keep down for an entire four game series.
But with Kenta, I just think there's a level of production that he's going to have to hit in order to maintain his position, even with his salary and other considerations. Especially if they hang around in this division for any length of time. Manning is too good of a pitcher and the options behind him (ie. Jobe) are lurking as well