Dolphins have the most underrated group of corners in the entire NFL. We've got 3 (Will Allen, Andre Goodman, Travis Daniels) #2/3 corners and some talented wild cards in Jason Allen and Shirdonya Mitchell that could be very good. I'd go as far to say, that we have some of the best depth at the position in the entire NFL.
Do we have the best group of corners in the NFL? Of course not, but we're not as bad as having the 14th ranked set of corners in the AFC. It would be more accurate to say we should rank around 14th in the NFL.
Teams that they ranked ahead of us and how their they did defensively last year:
Bengals: 62.88 completion % (349/555), 7.26 ypa, 24 touchdowns, 19 interceptions.
Texans: 65.08 completion % (328/504), 7.21 ypa, 22 touchdowns, 11 interceptions.
Titans: 63.02 completion % (334/530), 7.08 ypa, 24 touchdowns, 17 interceptions.
Then there's the Dolphins...
Dolphins: 55.82 completion % (278/498), 6.58 ypa, 22 touchdowns, 8 interceptions.
Goodman's shoulder is a concern, but the same shoulder bothered him last year and he did fine, I wouldn't expect a dropoff this year. Travis Daniels is finally at 100%. As far as depth is concerned, Jason Allen/Shirdonya Mitchell should be a substantial upgrade over Eddie Jackson/Michael Lehan.
Our secondary as a whole should be better than it was last year. I expect about the same completion% against, a lower ypa against, fewer touchdowns against and more interceptions.