Likely R. In recent times, the "only won because their opponent was nutty/incompetent" effect is about 10% of the vote and he only beat Bevin by 0.4%, so I think the baseline expectation for 2023 is an 8-10% win for Generic R. Of course, JBE did just get reelected, but he managed to beat scandalized Vitter by 12%, suggesting he may have won anyway against a Generic R back in 2015.
I mean... a lot of what you said is just true and I would agree JBE may have a shot against a generic R in 2015. But look how much changed from 2015 to 2019. Who knows how the climate will be like in 2023.
For all we know Beashear is elected by a 10 point margin due to lopsided margins in the Cincinnati burbs.
Also, not all midterm and off year elections will necessarily go against a presidents party. Though the 2002 GOP wave was over stated.
I mean, he obviously has a better chance with a Trump reelection than with a Dem president and an economic crash, but I don't see any way he goes into 2023 favored for reelection.