To be honest, I’m a little surprised John Lynch and Kyle Shanahan haven’t made a trade for Mack yet. Through three weeks, the 49ers have already marched out a carousel of running backs, with Raheem Mostert, Elijah Mitchell, Trey Sermon, JaMycal Hasty and Kyle Juszczyk all taking snaps in the backfield. Mostert was lost for the season after logging just two carries in Week 1 with a knee injury, Hasty landed on IR with a high-ankle sprain ahead of the Green Bay game and sixth-round rookie Mitchell missed Week 3 with a shoulder injury. Sermon had 10 carries for 31 yards and a TD as the featured back Sunday, but Shanahan’s offense, which is averaging 105 rushing yards per game, deserves more production out of the position. Kerryon Johnson was promoted to the active roster prior to Week 3, though he didn’t get any carries Sunday night. Still, it feels like a no-brainer to trade a late-round pick and secure Mack, a more proven player, as a one-year rental.
