The rationale here is pretty simple. The Baltimore Ravens are pretty banged up and the San Francisco 49ers defense is playing poorly. Steve Smith Sr. will miss another week of action with his back injury.
The backfield is a different story though, as Lorenzo Taliaferro was placed on the injured reserve as he must have encountered a serious setback with his foot injury, and Justin Forsett is still not 100% after suffering an ankle injury towards the end of last week's game against the Browns, though it should be noted that he practiced on Friday.
Enter: Javorius Allen, also known as Buck Allen. He should get a decent amount of looks as Forsett was already not getting the bulk of goal line and short yardage work, and now Allen has no competition for spell-back duties.