In terms of the team this year, the median age is what it is. But I think roster construction and playing time is worth paying attention to.
The age cutoffs are somewhat arbitrary, but. . .
The Sox have signed/acquired a number of vets at the end of their careers for stopgap stability:
Turner - 38
Kluber, Martin - 37
Bleier - 36
Jansen - 35
Paxton, Duvall - 34 (both on 1 year contracts)
The also have some older/prime-year guys who they found/signed as role players:
Sherriff - 33
Refsnyder - 32
Ort, Bernardino, Joely - 31
Tapia, Reyes - 29
The long term core is younger:
Verdugo, Wong, Whitlock, Houck, Crawford - 27
Devers, Duran - 26
Winckowski, Murphy - 25
Bello - 24
Casas - 23
But there's a real gap for key players in the age 28-33 bracket.
Hernandez - 31 (1 year contract)
Pivetta - 30
Story - 30 (long term)
Yoshida - 29 (long term)
Schreiber - 29
McGuire, Arroyo - 28
Which is basically 2 key players in Story/Yoshida, and three key secondary players (McGuire, Arroyo, Schreiber).
Pivetta who pitched himself out of a starting role, but is a nice bullpen piece, can't really be considered a key player going forward. Likewise Hernandez who is a defense first CF.
***
Or consider games-played this year: Players who have played half the games over age 28:
Refsnyder - 49
Yoshida - 69
Hernandez - 71
Turner - 76
Age 28 or under:
Arroyo - 44
Wong - 59
Duran - 60
Casas - 70
Verdugo - 72
Devers - 76
TLDR: The roster paints the picture of a mostly younger team, stabilized by a handful of older vets who are on short-term deals.