I would say "how quickly we forget" except Pettis fights so seldomly that you guys haven't forgotten "quickly."
Pettis v. Bendo 1 was a close fight that could've gone either way. The kick secured that 5th round otherwise, there's a very real possibility Bendo gets that decision. Then Guida made Pettis look like a chump and Stephens gave him all kinds of problems and can be argued to have been robbed on that split decision.
Since then Pettis has only had 4 fights. Lauzon, Cerrone, Bendo, and Melendez. Cerrone was in the deepest part of his YIPS phase and Bendo got caught early with a slick armbar. There's no doubt that Pettis is a talented and athletic guy but let's not act like he cleared out the LW division or anything. He got leapfrogged past a ton of guys due to his last WEC fight, not for anything impressive he did in the UFC at the time.