I think the differentials are so small between the 3rd, 4th and 5th slots that saying they are all very important run-producing slots is always going to be true.
I was a firm believer in the 3 slot for your best all-around hitter for decades, but I trust the studies. It's not something I will go to my grave defending, especially because the differentials are very small.
I think we've beaten this subject to death, but I will add two points:
1) Taking away the first inning seems to favor the idea that the 4th hitter is more important than the 3rd hitter, who has these 4 guys up before him: 8, 9, 1, 2, while the 4 hitter has 9, 1, 2, 3 and the 5 hitter always has 1, 2, 3, 4 before him, counting the first inning- all the best hitters on the team.
2) One question I'd ask about these studies that show the 3rd slot hitter should be your 5th best hitter is this: did the study differentiate between great hitting teams and poor ones? When you have a team with 5 guys with an OBP above .350 and an OPS above .800, maybe the numbers change. Maybe teams with crappy hitters skews the numbers.
I'll not complain when JD bats 3rd. I think Cora knows what he's doing, and right now Betts, Bogey, JD and Devers are pretty interchangeable, except for the speed component, so there shouldn't be much swing anyway we go. (Even Beni is heating up right now.)