To me, the issue is still best player available at 28 or trade down.
Best DE left on board at 28? How much better will this guy be than the speed rushers in round 2? What's the chance this DE actually shows up and wins a starting spot over DLaw, Mayowa, Irving, Tapper. Unless you get a true speed rusher, a rookie DE is more likely a guy who is working to gradually make the rotation.
Best CB at 28? Still clearly a tier 2 or 3 CB at the bottom of round 1. Jackson can impact as a rookie in return game. King may be a better match up with big receivers in NFC East. But again, is a rookie CB taken that low going to beat out the vets Scandrick, Brown, Carroll?
I think a rookie CB probably has a better chance of winning a starting spot than a rookie DE unless a pure pass rusher drops who can be on the field every 3rd down. I think we have to take the best player at 28 because neither key position is likely to make a huge impact this year, though you never know for sure.
You can't really make the call until you see what's happened in picks 1-25, but I think I like the idea of dropping into the top of round 2, possibly getting both a CB and DE in round two, 2 guys very similar to whatever you would have taken at #28.