He's mediocre in coverage, with poor instincts for the ball. He also tackles poorly and never wraps up. So far, his only saving grace is his 40.
If we went secondary in the first, it should be either Leon Hall or Damien Huges. With safety being as deep as it is, a potential shutdown corner in the 1st would make more sense.
I see Merriweather being the next Ed Reed. A ballhawk with great speed and some good hits in him.