I reviewed Carr's 2016 play and posted analysis with (Q,T) references here:
http://russellstreetreport.com/2017/03/20/filmstudy/ravens-brandon-carr/
Cliff notes:
The Ravens are set for a big pass rush improvements from personnel in secondary
Ball skills on defense are concentrated into just 4 players (Weddle, Young, Smith, Mosley), which is scary for a team that has gone from a historically bad INT total in 2015 to the NFL leading interception rate (3.11%) in 2016.
Carr is a pure press corner who is selective in applying hands (more often vs smaller receivers) and stays with a receiver well in straight line coverage using bump-and-run techniques.
Despite a coverage style which involves significant hip and elbow contact past 5 yards, Carr has reduced his penalties over 2014-16 from 12 to 6 to 3. He was penalized 3 times for DPI, but did not draw a single flag for iC or DH in 2016, which speaks to an understanding of how the game is called.
Carr avoids tackling contact with RBs (or as 2nd man to the ball) to an extreme degree, which may be the secret to his durabilty.
He played primarily RCB for the Cowboys, but with Claiborne out vs the Bucs in week 15, he followed Mike Evans on the bulk of plays.
The team-friendly contract allows the Ravens to consider undervalued, developmental, or injured CBs in this year's draft.