Eli does have a ring and a SB MVP trophy.
Cassel, while having great numbers, benefited from an outstanding scheme (I know very well, as a ND fan). That system is made for QBs to look good, but specially last year, it didn't require him to complete much passes beyond 10 yards, as evidenced by him achieving less than 3200 yards and having a putrid 6.9 YPC. Oh, and he completed only 4 passes of over 40 yards, one of the lowest amongst starters. And he completed below 60% of his passes. What does it say? He didn't take many risks throwing long passes, and he still wasn't very accurate. Truth of the matter is, he was a glorified game manager who couldn't win games by himself, because the team relied heavily on it's running game. And he played against some awful defenses.
But that's not why I say he's no deserving. It's because I've watched some of his games, and he was nothing special. More importantly, when it mattered, he was plain awful, completing only 9 passes and throwing 3 ints against the Ravens. The Ravens took the running game away and forced him to beat them. He didn't come even close.
The way I see it, Cassel is a guy that you can't win a championship with. Matt Hasselback in his prime was a better QB. Cassel can be an excelent backup, he won't cost you many games, but you can't count on him to win games.
Maybe if he gets an elite D and an elite RB like the 2000 Ravens he can win you a championship... Dilfer did it.