We need a RB at this point, though I am not sure Mr. Unga is the answer. This Ronnie Brown thing should really be bothering people. He is unsigned and does not need to sign until the start of the regular season. Otherwise we are left with fading Ricky Williams, Cobbs coming off of a season ending knee injury, and Hillard.
Unga is a talented kid, but the fact that he is injury prone leads me to believe Miami will not use a draft pick on him. There is a question about his speed also.
As far as Ronnie not being signed yet, I understand why Miami has not signed Ronnie yet. Brown probably wants elite level money, and while he may be an elite talent, he has not been able to stay healthy.
As far as Ricky Williams is concerned, the "fading" RB was the 10th leading rusher in the NFL last year with 1,121 yards on 241 carries and a 4.7 yard average and 11 rushing touchdowns. You don't won't Ricky carrying the load at his age, but he still is productive.
I definitely look for Miami to draft a RB in the 2011 draft.