Rookie Jay Ajayi could begin practicing this week for the Dolphins. Steve Mitchell USA TODAY Sports

Coming off of their best rushing attack all season, the Miami Dolphins are about to add another talented back to the roster. Rookie running back Jay Ajayi was placed on short-term injured reserve to open the season, and while he's no eligible to return to game action until Week 9, he can begin practicing this week.

Ajayi is a promising back who's draft stock plummeted late in the process due to concerns about the long-term health of his knee. It remains a concern, but it also allowed the Dolphins to take him in the fifth-round rather than the second, which is where he was expected to go.

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It wasn't the knee that forced him to start the season on IR, though. It was a broken rib that delayed his NFL debut. It's not a serious, long-term injury, but it was enough to sideline him for an extended period of time.

When Ajayi does return, he'll need to carve out a role for himself in a backfield that's fairly crowded. Lamar Miller isn't going anywhere, while Jonas Gray and Damien Williams have both made impacts for the Dolphins.

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