CHARLOTTE — Panthers head coach Dave Canales continues to be impressed by the level of attendance at voluntary OTAs, but he was without a couple of young offensive pieces in Tuesday's session that was open to the media.

Rookie wide receiver Jimmy Horn Jr. was sidelined with a recent hamstring strain, and Canales said he was working his way through their return-to-play protocol.

"We're just rehabbing him," Canales said. "He's in return to play, and then as soon as we feel like he's ready to get back out there, we'll bring him back out."

The sixth-rounder stood out in rookie minicamp, and Canales said that as he worked through the offseason, they envision specific things he can offer to the offense.

"Yeah, Jimmy gives us a lot of options," Canales said. There's some perimeter things we can do with him, the jet sweep game, but then also, like just from his college film, he's a receiver first and foremost.

"He can stretch the field. He can separate, and he's got a lot of energy and passion he plays with, so he's going to give himself a great chance to help us."

Veteran tight end Tommy Tremble will be out of action until at least the start of training camp after having back surgery recently, and Canales offered a little more clarity on his situation as well.

"I don't know specifically what the timeline is; there's a window in there he could get back to us at some point as we go into the preseason in camp, but right now, it's just like we have to take it one day at a time," Canales said. "He feels great, but there's a lot that goes into that, making sure that he's right, and so we'll kind of just take it day by day as we go."

When asked why Tremble didn't get the surgery earlier in the offseason, he explained that the fifth-year tight end felt things change over the course of the spring.

"He would come out and say he'd feel great in practice, but the minute that he would cool down and kind of sit around, it just was so uncomfortable," Canales said. "It's just not a great place to be. We thought with having some time right now, like the sooner, the better. So it wasn't something we were super concerned about early on, but, you know, kind of we all put our heads together, and we talked to Tommy and involved him with the decision as well, of course, and we all thought that it was the best thing."

The Panthers had a few other players missing Tuesday, but Canales said they were mostly for personal reasons.