I wonder if this is an accurate analysis of Watkins (Height: 6-5/Weight: 212) prior to the draft:
POSITIONAL FACTORS
Grade * Category * Comments/Description
5.5 * Read & React * He usually reads and reacts quickly to the play, but he struggles when he has to change directions fast.
6.0 * M/M Coverage * His long legs hinder his ability to cover receivers in man-to-man coverage, but he is athletic enough to cover tight ends.
5.5 * Zone Coverage * Watkins does a good job breaking and closing on passes in front of him, but struggles on outside throws.
5.5 * Break and Close * He can break and close fast up the field, but struggles to burst and get outside to help with over-the-top coverage.
6.0 * Hips/Turn Ability * Despite long legs, he is surprisingly good at flipping his hips to turn and run with a tight end in tight man-to-man coverage.
5.5 * Tackling * He has the ability to be very good, but when he gets out of control, he often dives/lunges and misses tackles.
5.5 * Hitting Ability * When he stays over his feet and under control, he can be a strong and violent tackler/hitter.
5.0 * Hands - Interception * He has adequate hands at best and has not shown the ability to make the tough interception.
5.5 * Hands - Fight Blocker * He does not consistently compete hard and fight through blockers. He often gives up and gets blocked out of the play.
6.0 * Deep Speed * He has the playing speed to stay on a tight end's hip in man-to-man coverage deep down the field.
NA * Return Ability * In the games graded, Watkins did not return punts or kickoffs.
5.0 * Errors * He gets out of control too often and ends up missing way too many tackles than are acceptable.
LINK
He definitely has areas which he has to improve upon, but his weight and height do not appear to be really hindering factors.
"Too skinny?" I don't think so.