I defer to no one on complaining about JBJ, who I don't think is the best Sox CF ever or the best CF in the AL or MLB today. Plus his hitting is just miserable.
All that said, right now he's not a bad fit as the Sox starting CF because the three subs are Leon, Pearce, and Nunez, none of whom are hitting well. Plus JBJ in CF solidifies a pretty solid defensive outfield and lets JDM be the DH. Most times, Cora can go with 8 other guys over .800 OPS (Beni, Betts, JDM, Moreland, Bogie, Devers, Chavis, and Vazquez) in the lineup plus JBJ with his miserable .450 OPS.
When Holt gets back, maybe it's a different story, but right now I'm fine with JBJ in CF despite by attacking him continually on this very thread.