Based on what metric? Unless he goes to a team in QB hell, before his rookie contract is up, he'll be out-performing anyone we could conceivably have on our roster opening day of next season. He is the best WR in this draft, is noted for being an excellent route runner, comes from a well-coached program, doesn't have a habit if taking plays off, has plenty of height, can line up anywhere and still be effective, and is undoubtedly fast enough to make it in the league (hell, he was timed at a 4.35 40 at 'bama).
I don't know what you look for for a potential #1 WR, but by every metric I see he has what it takes to be one. Unless you are holding his underwhelming QB year against him, or you are looking for a guy who will nominate from day 1 (which is rare at the position)I don't see how you can knock his game.