Johnson is dealing with a foot injury, The Miami Herald's Adam Beasley reports.
With Jay Ajayi, Damien Williams and Kenyan Drake all locks for the final roster, Johnson is left to compete with Senorise Perry and De'Veon Smith for the No. 4 spot on the depth chart -- a slotting that doesn't guarantee him a job. Even if his injury clears up quickly, Johnson will face tough odds to make the team.