This is exactly why I like the advanced defensive metrics and WAR.
WAR actually does show that at his current abysmal rate of offensive production, JBJ can't really make up for it with his defense.
Duran's current fWAR is +0.5 and JBJ's is -0.5.
He was throwing the change-up in his last rehab start.
https://www.boston.com/sports/boston-red-sox/2022/06/25/chris-sale-rehab-outing-red-sox-rib-cage-injury-update-return-portland/