I'm not concerned about Xander only having 7 HR and 37 RBI and JD only having 9 HR and 38 RBI.
1. RBI is a function of the guys hitting in before them. Hitters 9 and 1 have been not great. Kiké was poor for long stretches and they stuck with him leading off.
2. I think I'm not surprised by JD's power decreasing. 481 SLG this year. His SLG from 5/1/21 - 10/1/21 was 473 with 19 HR. He had a strong April, but tailed off afterwards. He's just continuing that trend. Even so, he has a 137 wRC+ which is solid. Not great for 20M, but solid.
3. Xander has matched the 137 wRC+, which is second highest of his career. I don't know if I could expect much more out of him. Great batting average and OBP. If he continues this pace, he'll have a career best fWAR. hard to complain.