Mostly agree with your rankings; with the optimism bias from being a cardinals fan personally, I'd argue you could make a 1 star increase at each position, but their current rankings are also fair. I very much disagree with the 1 star ranking at special teams however, as we have a pro bowl gunner in Justin Bethel being joined by some high upside athletes in the kick coverage team and kick return game. Probably the best coverage unit in the game, which coupled with a punter who is below average (don't think he's as bad as stats show- his hangtime is rediculous, and it seems the staff went with him for this reason. I'd choose a distance leg with our coverage team, butI digress). In short, I'd say 3 stars is fair. A perfectly average special teams unit, whose only limitation really seems to be Drew Butler's distance and the uncertainty of a new long snapper (but both seem pretty reliable this far)
Tons of experience at multiple positions on DL (DT, DE, 5-tech)
Strong work ethic
Nice initial pop
Highly inconsistent and can take some games off (not plays - whole games)
Doesn't always play as big as he is
Motor runs hot and cold
Not a fluid athlete; a little stiff
Lacks a pass rush repertoire
Doesn't make much of an impact rushing the quarterback
Below average production
Summary: I don't think a player's stock has fallen on my board over the summer more than Heyward's. I went into the summer expecting to see a first-round pick on tape, and instead I now see a second-rounder. He gets dominated by inferior competition and should be more dominant on a more consistent basis when you factor in his size, strength and talent.
Heyward's best fit by far at the next level is the 5-technique position (3-4 DE), and I just don't see him being an impact pass rusher at 4-3 left defensive end. Heyward needs to step up in his senior year if he wants to be a top 25 pick. As I mentioned previously, Heyward is starting the 2011 season with a second-round grade on my board.
Player Comparison: Kenyon Coleman. Coleman is a strong player against the run for the Browns, but he's a little inconsistent and doesn't offer much in terms of a pass rush.