The Jazz basically have lost two of franchise's all time best 3pt shooters in Korver and Okur. DWill was also a reliable shooter especially in clutch moments. It was obvious that the lack of consistent shooters who gets attention of opponent defenses would create some offensive problems.
The coaching staff knows it very well, and they could've prepared for Zone; after all the Jazz are not the only team in the NBA that is over-dependent on inside scoring. IMO, having just 2 preseason games + little time to work on offense in training camp (because Corbin put all the emphasis on defense, which has vastly improved compared to previous seasons) prevented such a precaution and is the main reason for inability of the team to execute against a Zone.
I'm not ignoring the fact that the Jazz need consistent shooters, not volume shooters who needs to shoot many to be efficient, and I'm not criticizing the management for not bringing in shooters to replace the production of Kyle, Memo etc.
As I said before, if the Jazz really want to make a push for playoffs -which is not easy considering how tough the West has been and how favorable the schedule has been for the Jazz- they need a scorer shooting guard.