Christian McCaffrey explains not playing season opener, plans to play Sunday

49ers running back Christian McCaffrey was a surprise inactive after the team listed him as questionable in the lead up to Monday night's opener. It came after McCaffrey said in his media availability that he was playing.His calf strain and Achilles tendinitis said otherwise, deeming him unavailable. Coach Kyle Shanahan said if it had been a playoff game, instead of the first of 17 regular-season games, McCaffrey would have played.Despite running back Jordan Mason saying he learned he'd be starting on Friday, McCaffrey insists he didn't know until Monday."I prepare every week to play," McCaffrey said, via David Bonilla of 49erswebzone.com. "My mindset every week is I'm going to play. There's been weeks where I'll go the full week, not even feeling good enough to do the walkthrough, and then I wake up, and the body's capable of a lot of cool things. Mentally, I'm always prepared to play, and then woke up [on Monday], and it was a group decision, a very tough one."I hate not playing, but I look at it as a chess move, something that, hopefully, we can benefit from the rest of the season."McCaffrey said his current injury is unrelated to the one he had in Week 17 of last season."It's...