It is customary for the NFL and teams to have contact after games about injuries. However, there is no indication that the league has launched a formal investigation into the San Francisco 49ers over the injury designation ahead of the team’s season opener, a league source said Tuesday.

McCaffrey was officially listed as questionable ahead of the game against the New York Jets. The accuracy of that designation was called into question Monday night after backup Jordan Mason, who rushed for 147 yards and a touchdown, said he was told he would start Friday during a postgame interview with the broadcast crew.

49ers coach Kyle Shanahan said after the game that he did not tell Mason he would start, but instead told him to be ready because he expected him to play more. Mason declined to comment further in his postgame press conference about his comments to the broadcast team.

McCaffrey is “day to day” with the calf and Achilles injuries that kept him sidelined, Shanahan said Tuesday, but he could have played if it had been a playoff game.

“You know, it’s not just a calf. It’s his Achilles tendon and, you know, the Achilles tendon has tendonitis and things like that come and go,” Shanahan said. “And when it does flare up, you have to be very careful with that. Christian is pretty diligent with those kinds of things.

“And if it was a playoff game, he made it very clear to me – he believed he could go. But you hear things like that and it’s not a playoff game and it’s Week 1, especially when you’re dealing with the lower extremities, it was a tough decision, but when you hear all those words and things like that, it made it easy in the long run.”

McCaffrey was able to train only to a limited extent in the run-up to the match.

Shanahan called the calf/Achilles issues that kept him out of training camp “similar” to the calf injury he suffered in Week 17 of last season. He did not play in Week 18, despite San Francisco resting most of its starters for that game, but returned for the divisional playoff game against the Green Bay Packers, rushing 17 times for 98 yards and catching seven passes for 30 yards.

Required reading

(Photo: Lachlan Cunningham/Getty Images)