sorry but there have been plenty of rookie RB's who tear it up in their first year (some high picks some not). WR, and being a #1 WR, in the nfl is a totally different beast and i put more worth on a rookie WR doing it because it doesn't happen often
Lacy and Stacy are carrying their offenses for teams playing backup QBs. Allen is a cog but Rivers is the guy running the show