Football is not basketball.
Of course Sidney Rice has an advantage because of his size. However, guys like Al Harris have proven that they can cover big, 6'4" 200 - 230 lbs guys. In fact Al Harris is a 6'1" 188 lbs guy and he covers them like none other.
Jarrett Bush is a little bigger, 6'0" 197 lbs, he has all the physical tools but his head might not be where it should all the time. I think Bush is a real talent and might some day when his head and body starts working together consistently, emerge as a very good corner. In a different thread I called for bringing back Patrick Dendy, and I still believe that. What I however didn't call for was cutting Jarrett Bush.
Tramon Williams seems to have very limited talent except for returning kicks, so does Will Blackmon at the moment, but in addition he also seems to be extremely injury prone, so in my view, there is no one to push Jarrett Bush for his job. A competition between Jarrett Bush and Patrick Dendy would make them both better corners. Dendy didn't look very good in camp, that is true, but he never looked very good in training, not even last season, when he after all played pretty decent. I was sorry to see him go because I think there's something to him.
In the long run Jarrett Bush might become the better CB, Bush might become a playmaker and a top cornerback, in Dendy I only see a solid nickel down the road, but today, the competition Dendy brings would only make Bush and this team better.