I'm hung up on the idea of defining a number one wide receiver. In a way, it's easy to define. Like the Supreme Court once said about pornography (they were actually referencing community standards), you know it when it you see it. That somehow lacked the definitiveness I wanted.
As for one of the St. Louis Rams' newest wide receivers, the Supreme Court definition doesn't tell us anything since we haven't seen Austin Pettis line up against NFL competition...yet. Hopefully, by next year we'll have that opportunity. Digging around some trusted sources, I did find some answers. In a draft valuation pyramid posted a year ago, Walter Football ran down each position. As for the #1 wide receiver, there's one standard.
...the most important thing a No. 1 receiver does is he completely changes the defensive play calling. You will see a lot of bracket and double coverages, which leaves open other receivers on the field and enables the potential for a quarterback to shred a defense.
Secondly, a No. 1 receiver simply makes big-time plays. Whether it is getting huge chunks of yardage after the catch, going up and getting a "jump ball," making clutch grabs or scoring touchdowns, there is no doubt that this position is one of the most coveted in the NFL today.
As you might imagine, it's not a real common occurrence to have a wide receiver like that. And they're not invincible either. For instance, Rams corners limited WR1s to -17.0 percent DVOA, 5th best in the NFL. But that's not the point here...
Getting back to the original Pettis question, I just don't think he has the complete package to command double teams and change the way a defense plans it approach. However, the tough catches and ability to score touchdowns does seem to be one area where Pettis has real potential. Take this other tidbit:
Receivers are a tough position to scout (mainly because the NFL puts way too much of an emphasis on size and athleticism, and not enough on route running and hands - which is why DeSean Jackson lasted so long in the second round)...
Teams miss excellent wide receivers in the draft all the time, leaving them on the board for too long or picking the wrong ones too high. If a prospect has the qualities mentioned above - a strength of both the receivers and the tight end the Rams drafted this year - they can develop...maybe not into a Larry Fitzgerald, but into a talented contributor, think of it like a WR1a.