NFL.com has him ranked at 72.
Strengths
Elite size with premium athletic traits that should show up at combine testing. Four-year starter. Sharp focus when ball is in the air. Takes path to the ball with undercut of the route at the last second. Plus hand-eye coordination to flip the field with interceptions. Former cornerback who has the athleticism to cover matchup tight ends and some big slots. Posted six interceptions over last two seasons. Uses big frame to body-up seam-runners and constrict their windows.
Downhill tackling machine. Plus range with a wide net to bring runners down once he gets his arms into them. Body-up hitter. Drastically reduced penalties totals over junior and senior season.
Weaknesses
Leggy and gets feet bundled up when asked to turn and sprint. Lacks desired instincts and will play with slow eyes at times. Has to see ball in the air before charging over to help on deep throws. Inconsistent with coverage responsibilities from high safety. Takes time to diagnose play-action. Rub routes found him near goal line. Can take inefficient paths to the ball that get him there a step too late. Would benefit from high-pointing rather than waiting on throws.
Sources Tell Us
"He's a freak. He's going to blow away the combine. He's fast and will post some of the best vertical and broad numbers at his position.
He's going to get a lot better in the pros and he has that elite size that will get him overdrafted." -- AFC Pro Personnel Director
NFL Comparison
George Iloka
Bottom Line
Big and athletic, he may lack the coverage qualities and instincts needed to work as a "last line of defense" player in a pass-happy division.
Melifonwu is an effective downhill tackler who has the ability to match up against tight ends and make a living near the line of scrimmage. His football instincts aren't up to par, but the size and traits will be extremely enticing for teams who covet traits first.
http://www.nfl.com/draft/2017/profiles/obi-melifonwu?id=2558189