Certainly 2016 numbers for some of our younger players might end up being outliers or career highs, but normally players continue to improve from ages 22-26 or 27. Not everyone does, and there are usually some ups and downs along the way.
The striking decline from 2016 to 2017 by every single Sox player, except Vaz (who still sucks at the plate) is what is at question. We don't have any hitters older than 33. Even HRam, Pedey, Moreland and Young are not significantly post-prime, and yet all of them, except Moreland who wasn't here last year have declined from 2016.
The "career norm" numbers for younger players often skews the total downward due to struggles in the earlier 1-2 years of their career. That is part of the reason we continue to see players do better than their career norms as they progress from year 2 to year 4 or 5. But, the other part is that players normally improve from year-to-year until ages 26-29. Of course, there are players who do not follow the age curve norm. Some have great starts and never come close to those numbers again. Some improve after age 30.
Some players moved from one age group to the next, but these numbers are telling for our pre-prime and prime year players:
Age group OPS
2016>2017
18-25: .807 (1917)> .769 (1468 PAs)
26-30: .759 (1968)> .658 (1237)
31-35: .796 (1809)> .761 (1335)
36-45: 1.021 (626)> N/A
Nobody expected every young player to improve on their 2016 numbers, but I do think it was reasonable to expect a couple to do so, of that the aggregate numbers of our players under 30 would be someplace close to 2016 numbers. The full season from Beni could have made up for some drop-offs by others.