Looking at his
stats it looks like you are looking at his third year as a starter, 1997. He starterd 16 games in '95 and 14 in '96. In looking at those stats he killed it in his first year as a starer, '95, 32 TDs and 12 INTs.
After that though, he was pedestrian to awful. I am not defending Cassel here at all. His inaccuracy is some of the worst in the league for a starting QB. But, I think the best case scenario is with him getting a QB coach, correcting some of his flaws and being a serviceable starter. I never see him as being even a second tier NFL QB.