Anquan Boldin ran a 4.8, Terrell Owens ran a 4.6, and there's a long list of others who ran a 4.5 which is around what Green will probably run. With a WR, it's not about how fast you are, it's about how good of a route runner you are.
As for the Hybrids, Clark and Shockey both weigh 20+ more pounds than Green. And grahm weighs 30 pounds more than Green. He should be an effective blocker in the NFL but I don't see him lining up on the line as a TE. Look at colston. He was a TE at hostrfa and he is 6-4 225. For the record, Green is 6-6 230.