PITTSBURGH — Pitt hasn't had many defensive players as productive as linebacker Scott McKillop, who often looked as though he intended to make every tackle on every play. Some games, it almost seemed as if he did.

Now that he's graduated, the Panthers realize it will probably take more than one player to replace him. So here are two of them: sixth-year senior Adam Gunn and freshman Dan Mason.

Gunn and weak side linebacker Shane Murray each missed nearly all of last season with injuries — Gunn with a broken neck, Murray with a torn-up knee — but both are back. Gunn, hurt during a helmet-to-helmet collision with McKillop during Pitt's opening game loss to Bowling Green, successfully petitioned the NCAA for a rarely granted sixth season of eligibility.

First, though, Gunn went through an operation in which a titanium plate was installed to fuse the fourth and fifth vertebrae in his cervical spine. That's not exactly a sprained ankle.

Gunn's injury is one of the most severe a football player can experience, and the Panthers have yet to see how he will respond during a game — namely, will there be a hesitation to hit or a reluctance to throw himself into tackles?

But, only a few months after it appeared his career might be over, Gunn went through a limited spring practice without any problems and, so far during preseason camp, he has held off Mason to keep his starting job.

Doctors have told Gunn that playing can't do any additional damage to the portion of his neck that was injured.

"I just tried to stay as positive as possible," Gunn said. "I've always been a positive person, and that helped me from going crazy. I just hoped I would get a sixth season, and when it finally came through there was a lot of relief."