Kareem Jackson has by far the best cover skills of any defensive back drafted in this year's draft class. He has pretty good athleticism, an unusually outstanding route recognition skill, and great instincts and awareness in coverage. He also is a solid tackler and a decent run stopper. With the loss of Dunta Robinson to the Falcons, the Texans were more than desperate for help from their corners. Jackson might be the most NFL ready corner in this year's draft class because he was taught under a very good coach in Nick Saban, and he was solid value for the Texans at pick 20.
Tate has pretty good potential, for he has an excellent combination of size and (40 yard dash) speed, but I don't see that sub 4.4 40 when I watch him on the field. Which makes him a little overrated. He also isn't a tough runner despite being 220lbs. It reminds me a lot of Justin Vargas. But he is still very productive, he is a pass blocker, and he plays running back, a major position of need for the Texans. Overall, it was an alright pick, but below average value at pick 58.
Mitchell looks really underrated to me. I hardly ever got to scout him, but he has outstanding athleticism, but his stats are below average. But, with a closer look, I could tell that this was probably his first season as a starter and he was solid statistically, putting up Gerald McCoy like numbers. He got a lot of sacks last year but his tackle numbers were below average, and he needs bulk and height. A good pick here, and solid value at pick 81.
I always have considered Darryl Sharpton and underrated player. Sharpton is pretty short, but he is a tough, high intensity player with a high motor and good athleticism. He is also a very hard hitter (see: http://www.youtube.com/watch?v=rne2YpK-6cM), and he is very productive. But he has pretty awful instincts, and he lacks size. A good pick here.
Graham isn't an awfully strong blocker, but he is a solid route runner who plays hard and makes a fair amount out of his below average physical tools. He also has reliable hands, but he is awfully undersized and he may be better suited for fullback at the NFL level. A solid player here, and good value at pick 118.
I always considered Dickerson to be overrated, but even I can't deny that he was great value this late in the draft. Dickerson hasn't really been able to find a position, playing some tight end, fullback, running back, wide receiver, and linebacker. He probably has that "athlete" label that some guys have coming out of high school during the recruiting process like Russell Shepard. His speed is overrated; his 4.40 40 is great for someone of his size, but watching him on the field I would guess he runs a 4.55 or so. But he plays hard, and he is somewhat productive.