Smith is a prototype #3 fantasy WR. If you expect more, you're kidding yourself. He has some big games, but his normal games are almost never busts. How many fantasy WR's consistently get at least 40 yards receiving? Only the #1 WR's and the top #2's can boast more than ten 40+ yard games a year. It's the TD's that give them the big points. Jimmy isn't a major TD threat, but he does get a decent share.
I haven't seen many other guys who can consistently get 40-80 yards a game. Last year he had 3 games out of 16 where he had less than 50 yards. The year before was 3 of 12. In '02 it was 6 of 16 (although one was 49 yards).
From a #3, I'd take 5 points every week instead of 12 one week and 2 the next.
One disturbing trend to note with Jimmy is that a lot of his poor games come at the end of the year. I don't know whether it's him wearing down, playing in cold weather, or what, but it is worth noting. Possibly a caveat in buying him for the end of the year even with poor competition.