It's not a vague assertion. Asking me to compare Pickens to his peers has very little to do with whether or not the better WR's make difficult plays look routine. I don't think anyone is going to argue that.
Pickens is the Steelers #1 receiver, right? His targets say so, and he seems to think so, so those are his "peers". There are 18 guys with more receiving yards. When you include guys that started the season hurt or who have injuries, he drops even further down the list when you look at yards per game. Is he doing anything extraordinary after he catches the ball? Again, no. Only 67 YAC in six games. Takes plays off. Is problematic enough that they're, umm, "managing his workload". Give me a break. The guy just isn't what you want him to be. Can he be? Don't know. Hasn't shown that other than the occasional big play.
If you want to argue that the Steelers have put him in a bad position to succeed, so be it. They've done that to a lot of players under Tomlin and they've gone on to thrive elsewhere.