How does Foster fit into Miami's depth chart? Here's a quick player-by-player look:
Foster: He will turn 30 before the regular season begins, making Foster the oldest member of the Dolphins' backfield. Such age and experience can be valuable, but Foster will face doubts about his durability and ability to return to his Pro Bowl form. Recent NFL history offers few examples of rushers whose production has dipped only to spike again after age 30, although Foster can look to the resurgence of Chris Johnson last season in Arizona as a best-case scenario. If the Dolphins get that sort of boost from Foster, they would be thrilled.
Jay Ajayi: The spotlight had been on Ajayi, the Dolphins' fifth-round pick last season, to fill the void left by Lamar Miller's departure to Houston. Even with Foster now in the fold, Ajayi will still have a chance to earn the starting job, and he remains the top option to fill in for Foster if the veteran gets injured again.
Kenyan Drake: The Dolphins are hoping that Drake, a rookie third-round pick, can shake off some college injuries and become a productive pro. Drake was stuck behind T.J. Yeldon and Derrick Henry at Alabama, but the lesser wear and tear from not as many carries could work to Miami's benefit. The addition of Foster should also allow Drake to ease into NFL life as the No. 3 back in spot duty.
Damien Williams: Sidelined during practices this spring, Williams' chances of making the 53-man roster took a hit after Foster signed. He has played in every game since the Dolphins signed him as an undrafted free agent in 2014, but he didn't carry the ball more than four times in any contest last season. Unless there is an injury above him on the depth chart, that doesn't figure to change.
Daniel Thomas: The Dolphins brought Thomas back this spring after he spent last season out of the NFL. Thomas' arrow has been pointing in the wrong direction since he set career-highs as a second-round rookie in 2011. Foster's arrival dealt another blow to his chances of reviving his NFL career.
Isaiah Pead: The Dolphins are giving Pead, who carried the ball just twice last season for the Rams, another chance in the NFL after the 2012 second-round pick never found his footing in the league. Along with Thomas, he's a long shot to make the 53-man roster now that Foster is in the mix.