Agree on D.J. Hayden potentially being a surprise 1st. I could definitely see someone grabbing Tyrann Mathieu in the 1st though that'd be awesome. Da'Rick Rogers would be a good candidate too. Most of the surprise 1st rounders are guys with the talent but have red flags that were overestimated Pre-draft, or simply one team feels comfortable enough with them. Bruce Irvin was a 1st round talent but was never considered a 1st rounder because of all his character concerns like robbing drug dealers and smashing pizza delivery cars.
Agree with the people that have said EJ Manuel. I could definitely see a team like the Eagles trading up into the bottom of the 1st to take him. Some other intriguing names that could move up to the 1st round include Justin Pugh, Jamie Collins, and Sio Moore.