49ers provide injury updates on Mitch Wishnowsky, rookie Darrell Luter Jr.

Mitch Wishnowsky hurt his back lifting weights before reporting to the San Francisco 49ers this week. The punter may be placed on the non-football injury (NFI) list to start training camp. General manager John Lynch didn't sound overly concerned about the injury, noting that the team doesn't plan to sign a replacement for training camp practices.

"It's nothing we're concerned about long-term, but with the back, you want those things to quiet down," Lynch said. "If you don't, they can become chronic. So we want to put that to rest, and we don't think it's too serious."

We already knew the 49ers placed rookie defensive back Darrell Luter Jr. on the physically unable to perform (PUP) list. We just didn't know why until today.

"Now, Luter, in one of the last OTAs, hyperextended his knee," Lynch said. "It resulted in a deep bone bruise. He's working his way back, still has a few weeks. He's a kid who really had impressed us throughout the whole draft process, [and] then in his work here. Sharp kid.

"That's a tall order for a rookie, especially not getting all the reps. We believe he's somewhat 'we'll see.' He's got to prove it, but he's uniquely equipped because he's wise beyond his years, [which] has been our experience with him. Now he's got to go do it.

"I can tell you he never left here. His focus on the rehab was just excellent, so he's trending really well. But it is going to take some time. So not ideal, but that's where it is."

In April, the 49ers made Luter (6-0, 189) a fifth-round draft pick out of South Alabama.