Nice to see Scarlett getting some love. I don't like his odds to make the 53 man roster, but he could be a practice squad option. Another rb that I dismiss alot that likely has a better chance of sticking around is Patrick Laird. I think th team really likes Laird as a 4th rb who can handle 20-30 carries per season and catch a few passes out of be backfield. They might not see him as a fulltime rb option, but as a deep depth role I think the Dolphins are comfortable with Laird.
Gaskin and Brown are roster locks, the remaining rb battle with Ahmad, Scarlett, Laird and Doaks might not be flashy, but could be interesting to follow in training camp. I would also keep an eye out on the team signing someone either prior to training camp or after the other teams make their final roster cuts in September.