I would suggest that the Sox are as much sending JBJ a message as sending us a message. The message is, we no longer can claim we have any reasonable expectation of a rotation that we can plan around and therefore we no longer need to put a premium defensive CFer that is an unreliable hitter in CF every day. We can go with a "passable" defender in CF that is a more reliable hitter.
Beni would not be more than passible in CF and Mookie would not be more than passable in that position either. The problem with moving Mookie there is you move him out of the position he appears to have been born for.....RF and most particularly RF in Fenway Park. So if I had to guess, JBJ is gone. Beni moves to CF and the Sox get themselves a LFer that is a hitter from someplace.
Then again, Mookie might not be here in 2020 either.