Two random observations: The question whether the D is it sustainable plants a negative self-fulfilling prophesy in the mind of the reader. We know that no, it isn't. Now the writer's guild has something to jump on at every loss, and plenty of pots to stir about which coaches should be tarred and feathered, which players should be run out of town (or run over) on and on.
Next, expecting the defense to "sustain" at last year's level, sans Ramsey and Gaines to name two (Wagner was a one-year wonder, an outlier), is a pipedream beyond false expectations.
I expect the D to get scored against while new players learn, and to improve remarkably by season's end
IF most everybody stays healthy.
I don't expect Morris to all-of-a-sudden become more "imaginative," as one board member repeatedly puts it, with lesser personnel to utilize. Yeah, those safety blitzes, in the absense of pressure from the edge, are sure fun to watch when they get home, but they sure make you look silly when the throw goes into the open grass they vacate - and an unattended wideout is there to take another to the house.
I do expect Morris to plan to the strengths of his young defensive backs - especially as cordinated with his new D back coach. I expect some "dawg work" from the youngsters on the D line, led by their coach and AD. I expect Jones to play exceptionally well in the middle.
This is a new year with new personnel (a lot) and hopefully, new expectations that match the reality of our situation.
Bottom line, there is nothing to sustain.