Both players saw their contract expire after the 2010 season and it would be a major surprise if both of them were re-signed as free agents once the labor situation gets resolved.
On the contrary, it wouldn't be a shock if both of them played somewhere else next fall.
Versatile Patrick Cobbs also is a free agent and one would think he'd explore other possibilities to get more playing time on offense.
That leaves Lex Hilliard and Kory Sheets as the only running backs under contract, and Hilliard still is somewhat of an unproven commodity, while Sheets is a prospect coming off a torn ACL. The situation is more clear at fullback, where veteran starter Lousaka Polite returns.
It's no great secret the Dolphins need to add speed to their offense, and that includes the running back position. As accomplished as Brown and Williams are as players, neither of them produces many big runs.
If the Dolphins decide against bringing either player back, they'll need a bona fide feature back. Regardless, the Dolphins could use a speedy back, which is something teams will find in abundance among this year's draft prospects. As was the case last year, there's no need to use a draft pick on a fullback.