Cassel still has a lot to prove so I'm undecided. But he has shown some signs of improvement. Unfortunately the gameplan with Cassel is so conservative, he just has not shown any ability to connect on long passes and challenge the defense. The Colts game was the perfect opportunity to go long and get Moss involved, but we didn't go to him until the second half and by then it was too little too late.
The problem with Cassel is that he isn't good at reading the whole field yet and going through his progressions quickly enough to find the open man before the pass rush gets to him. He really needs to work on this if he is going to be able to throw passes over 10 yards, otherwise he's just gonna keep getting sacked. I think this weakness is one reason, though not the whole reason, why the playcalls went the way they did against the Colts.