No, Weeden DID throw the ball down field but people choose what they want to remember. Just like they don't want to remember that Weeden led a 91 yard drive to tie the game and completed passes of 17, 19, 24 and 28 in the process. All on the road in one of the loudest stadiums in the league.
The one thing Weeden did not to do is that he did not make any attempt to throw down he field to the wideouts. At all. Why? From my perspective, he likely has Garrett in his face all week telling him to play carefully, do your job and don't do too much, blah blah, and he likely decides that after practicing with Street and Williams for two seasons that they are not reliable receivers, they can't catch, and they will cause turnovers unless they are wide, wide open. Was he wrong?
Then Cassel comes in, figures hey, I'll come in and use all of the receivers on the field, and throws 3 interceptions that easily could have been 5. After that he was mostly a check down machine himself.