Raheem Mostert, RB/PR
Raheem Mostert has been with five teams in four years, but really came on last year as a special teams player and even as a running back.
On special teams, he had six tackles last year as a specialist. He really shines as a returner though where he has averaged 24.9 yards per kick return in his career. To give that some context, before Darius Jennings started as the Tennessee Titans kick returner last year he averaged just 22.6 yards per return.
With a good special teams coordinator and the right blockers, you might be able to get similar production out of Mostert if you think that the Titans need to load up heavier at running back due to a logjam at wide receiver.
As a running back, his actions has been very limited but last year he did average 7.7 yards per attempt on 34 runs which is a decent sample size.
The 49ers are stacked at running back and have plenty of receiver to plug in for special teams. Why not make a deal here to help both rosters get the best 53 on the field.