I'm thinking in the modern passing league (TEs posing as Wrs, scat backs, shifty slot WRs, etc. that you have to value the S position as much as the CB position in a zone defense. I know we played primarily man cover 1 last season out of necessity; playing to Carr/Mo's "strengths".
W/Carr and Scan as starters, you're going to have one weak zone CB (Carr) and one who can play both well but won't get you many INTs (Scan) with Mo (man corner) mixed in now (not sure why), it feels Marinelli's hand is being forced into man coverages over his primary preference and on top of that, with average man corners outside of Scan. I see holes in this secondary unless we get some decent zone corners in the draft (should be had later) and finally cut Carr w/Mo as 3/4th corner manning the outside in nickel formations (if he improves). Seems you would have to blitz a lot more than Marinelli is truly comfortable with (outside of the one WAS game last year).