Alexander is widely regarded as one of the top three CB's in the country. That's not the opinion of a Clemson fan—that's the nearly universal consensus among NFL draft scouts and experts. If you ask one of us, it's pretty clear that he's not only one of the top three, but the far and away the best.
He's really the only true shutdown corner in all of college football. The only other guy that is anywhere near his level in terms of coverage is Hargreaves III at Florida, but he's a junior as opposed to Alexander who is a sophomore after missing last year due to injury.