I think some people are misrepresenting some of the comments people were making when comparing Jeffery to Marshall. I think a lot of the comparisons stemmed from playing style, more than actual ability for the most part. If you watch a bunch of Alshon highlights, going back to college...there is definitely a comparison to be made about how they play the game. That isn't to say that the two are even remotely comparable on a skill level, although I do think Alshon will develop into a good / maybe even great NFL receiver.
Edit> Here is a good video....
[video=youtube;GTegYX4Gro4]http://www.youtube.com/watch?v=GTegYX4Gro4[/video]