Yes his stats show the proof. After 11 games he has:
Receiving - 42 receptions, 602 yards, 14.3 yards per catch, 5 TDs
Rushing - 11 attempts, 91 yards, 8.3 yard average
Kick Returns - 31 attempts, 924 yards, 29.8 yard average, 2 TDs
On Pace For:
Receiving - 56 receptions, 790 yards, 14.3 yards per catch, 7 TDs
Rushing - 15 attempts, 120 yards, 8.3 yard average
Kick Returns - 41 attempts, 1,213 yards, 29.8 yard average, 3 TDs
So it comes down to 2,123 combined yards and 10 total touchdowns. Not any other rookies puttin up those numbers
The NFL Gives out Offensive and Defensive Rookie of the year award, so i'm betting he is a lock for that.
NFL Network Combines all rookies and has the fans vote for rookie of the year by NFL.com website
Then The AP have all their Awards too. But Percy Harvin Should win all of theses if the process works