According to Cora, one path to improvement for the Sox is "to catch up with the speed of the game". He mentioned areas like defense and baserunning, and an overall lack of depth on the roster in '19 and '20.
Checking one aspect of speed -- stolen bases -- reveals a stark contrast in offensive strategy from '18 to '19. The champs were third in the MLB with 125 steals, and then only 17th the next year with 68 (they were 11th in the short season). What may be most telling is that every key baserunner had his number of swipes basically cut in half; here are '18/'19 SB totals: Betts 30/16, Beni 21/10, JBJ 17/8, Bogie 8/4.
It almost seems "restgate" extended beyond the pitching staff. But stealing bases was certainly contagious in '18, as guys like Nunez, Holt, and Kinsler nabbed 7 each, while Swihart and even JD stole 6 apiece. Whereas nine Red Sox stole 6 or more in '18, only four players had as many as 6 in '19.
In '20 the SB leader was Bogie with 8, then JBJ 5, followed by Verdugo and Vazquez 4 each. We won't replace Mookie, and it's not just about getting younger (can't steal first). But hopefully a hustling mindset can be reinstilled, if not reinstalled.