The defense is fine when we have the Beni/JBJ/Betts OF. It will be very solid when Pedroia is back because Nunez is horrible in the field. If he isn't hitting he's a negative.
Benintendi will hit better than he has, and I think its safe bet that Devers and Xander have good offensive seasons also. The lineup is frustrating right now, but there is no way it will be this bad all season.
There is way too much hope that Thornburg regains his 2016 form IMO. If he isn't dominant, this bullpen is worrisome. Kelly and Barnes are more of 6/7 inning guys and shouldn't be pitching in such high leverage situations. They are very shaky and completely lose the zone at times.