Kurtenbach: The 49ers use Christian McCaffrey like a rental car. He still looks early-season fresh.

There has been only one constant this season for the playoff-bound 49ers: Chaos.

Actually, check that. Make it two things: Chaos and Christian McCaffrey.

This season in Santa Clara has played out like a survival reality show. Injuries have turned the roster into a walking triage unit. Brock Purdy missed eight games. Four of the team’s five best non-quarterbacks were missing for Sunday’s game against the Bears.

By all laws of football, the 49ers should be spiraling.

And instead...