How much hinges on Christian McCaffrey?

Kyle Madson and Chris Biderman preview the San Francisco 49ers running backs ahead of the start of training camp with one important question: how much Christian McCaffrey do they need to make the playoffs? And are there ways to limit his use in the regular season to make sure he's available come January? That talk about Isaac Guerendo in Year 2, Jordan James prognosis as a rookie, and a lot more.