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)
Summary: Jeremy Beal is an interesting prospect in that while coming out of Oklahoma's hybrid defensive scheme can be a plus, where does he fit in the NFL on a team running either the 3-4 or 4-3? He was just good enough to be productive in a lot of areas at the collegiate level, but professionals are going to shut down a lot of what he was able to accomplish in Norman. For example, he is not really fast enough to make a smooth transition to outside linebacker and not really big enough to hold his down as a defensive end. His intangibles are his greatest asset because the team drafting him is going to do so because of his potential to overcome these obstacles.
Player Comparison: LaMarr Woodley. I hate to saddle Beal with a comparison like this, but in a lot of ways it fits. Woodley was another "tweener" coming into the draft with question marks about his speed and ability to convert to a 3-4 outside linebacker. He also has a similar frame. Beal would obviously love it if his career took the same path.