Most of the time, even the best WR prospects don't break out until at least their third year in the league. This can usually be attested to lack of polish, weak hands or the fact that they played in a non-NFL offense in college.
None of these are the case with Green.
He's very polished. The things rookie receivers struggle with the most is release off press coverage. Even stars like Calvin and Andre Johnson struggled with this in their first few years. But release is one of Green's strengths.
Whether it's using his elite quickness to get around a corner, using his frame to get in front of one or using his underrated strength to get through one, Green always seems to get a good jump off the line.
He has huge hands, and unlike most top receiver prospects who tend to lose focus (Julio Jones), he puts emphasis on catching the ball with his fingertips. He actually has some of the best hands of any prospect I've ever seen.
He also played in an NFL-style offense at Georgia that should be pretty similar to the West Coast offense the Bengals will run this year. He won't have to change his game to translate it to the NFL.