Edge is consistant but has no burst to the line.
Hightower has burst, but is inconsistant and lacks experience.
JJ lacks ideal size, but has burst, we've questioned his heart a number of times.
In a power-run offense I see 3 great rotational backs. Think of when the Eagles (grrr) had Buckhalter, Staley, and Westbrook. Look at what the Steelers had with Parker and Bettis and what they wanted to do with Parker, Mendenhall, and Moore.
The problem is that the Cards aren't a power-run offense. They're a barely-run offense. In that situation only a very elite few could create opportunities.
Unless Jim Brown and Barry Sanders want to come out of retirement, quit putting so much on the RB's and look at the problems up front.