49ers head coach Kyle Shanahan said Tuesday that running back Christian McCaffrey missed Monday night’s game against the Jets in part because it was the first week of the regular season.

McCaffrey was inactive for the game after saying last week that he had no doubt his calf and Achilles would be well enough to play in the season opener. Shanahan said after the win that McCaffrey was dealing with “a little too much“to come onto the field and the team “thought it would be smart to keep him out.”

During a conference call on Tuesday, Shanahan said, through multiple reporters, that the decision would have been different if it had been a playoff game and that McCaffrey would have been active in that case. Shanahan also said that McCaffrey has been dealing with Achilles tendonitis, which can be a bigger problem at times than at other times.

Shanahan has called McCaffrey daily this week, so another game call-up could come in Week 2 after a questionable listing.