Why? Simple...for two years Riley-lovers tricked themselves and tried to convince others how great it would be with a guy like Lee behind center, how his laser rocket arm would defeat all blitzes...how he could not only "sling it" like a pro but he could also "spin it" like a guy going 1/1 in the draft.
We were told over and over how he is not "a statue" but in fact had wheels that would keep defenses honest and with those wheels, we were told, from Langs that NU would not be abandoning the QB run game and that elements of it would still be used.
Riley lovers told us how when Riley get "his guy" the perfect slinger/spinner, Lee, that we would be seeing 70% completions and no picks...
So when you are told all this crap and you know it is crap ahead of time and then it is proven crap for a season and proven again now...you have fun with it. You make jokes. It is funny.