No, the Miami Dolphins do not need another RB but if they can somehow steal Josh Jacobs from the floundering Las Vegas Raiders, it would be a massive get for Chris Grier.
Jacobs is a phenomenal running back wasting away on the Raiders offense. Miami needs to look ahead. As good as they are right now at the RB position, Raheem Mostert is not a long term solution right now.
Mostert has an injury history and while he is playing fantastic right now, that history should be at least be taken into account.
I'm not proposing a big trade as Miami would need to lock Jacobs up for a few more years but pairing Jacobs with Achane for the future would give Mike McDaniel an amazing combination at running back long after Mostert leaves the team.
Will the Dolphins lock up Mostert for another couple of years? That is a big question that Grier needs to think about becuase right now, that is a stellar dua in the backfield but Jacobs would make them better, even as a three-headed unit.