Good article. http://www.nfl.com/news/story/0ap1000000230119/article/tyrann-mathieu-proving-arizona-cardinals-right-with-turnaround The whole question is whether he will hold up as a citizen. Moss did for a few years but when success came he got lax and became a headache. But, this kid is a player.
In any evaluation there is two parts. What is his ceiling and how likely is he to hit that ceiling. Opinions were wildly mixed on what his ceiling was, but they were pretty unanimous that his odds of hitting that ceiling were pretty low. It seemed to me that those championing his selection were content to ignore that second part.
I thought he was worth a 3rd, as did DJ, which is right where he went. Any third has about a 50/50 chance of being a multi-year starter at best as it is, so Mathieu's ceiling made him well worth the risk at that point. There were quite a few people who didn't think too that he had the skill set to be a regular starter and was probably a nickel at best. The things I read by the Cards' beat writers says he has already capable of playing corner, safety, or nickel. The kid is an incredibly quick study.
