Physical traits that time erodes include eyesight, muscle mass, metabolism... but factors beyond the individual obviously can greatly affect the individual.
When Raffy was having an absolute blast in his first few years, no one was counting on him to be another Big Papi. He was just another spoke in the monster tire, spinning through the batting order with the likes of Mookie, Xander and JD. In the World Series, at least, Devers was one of three "clutch" pinch-hitters, along with Nunez and Moreland.
Pitchers might have challenged him more in '17-19; it sure didn't seem like anyone could throw a fastball by him then.
For stat researchers, if possible, it may be interesting to compare types and/or locations of pitches delivered to Raffy then and now. Books on hitters also change as hitters adjust to books.
Right now, Boston has the majors' worst batting average in May with runners on base. If clutch isn't a repeatable skill, then team-wide suckitude for weeks must be a reflection of the roster.