FOR EAGLES tight end Clay Harbor, all this part-time linebacker stuff harkens to an uncharted and uneasy future. For Jason Avant, playing a little nickel corner takes him back to his past.

"I got recruited out of high school by most of the big schools to play defense," he was saying after yesterday's OTA concluded at the NovaCare Complex. "I was a two-way player. And I was All-American as a receiver and really close to making it as a safety. And most of the big schools saw me playing there."

Michigan didn't, which is one reason he went there. If Avant had his druthers, he'd always be lining up as a wideout on offense, a scenario that still seems likely when the Eagles play for real 4 months from now.

For Harbor, though, that is much less of a certainty, given the number of tight ends in camp, including second-round draft pick Zach Ertz.

For both, it is yet another portal into how their new coach thinks. And for those of us wondering how Chip Kelly was going to implement his system with a couple dozen fewer players than he could access as a college coach, well it's a portal for us, too.

Kelly didn't invent the multipurpose football player. Bill Belichick didn't, either, but his success in moving players such as Troy Brown and Mike Vrabel back and forth was surely noted by a coach who habitually visited Patriots camp during his 14 seasons as a University of New Hampshire's assistant coach.

Longtime NFL observers have questioned whether the pace Kelly sustained over four quarters at Oregon is a realistic approach for the big-boy league. Fewer players to practice with, fewer players to replace injured or exhausted ones, a disaster recipe amid the NFL's long, 16-game schedule.

There are 53 players on an active roster, eight on a practice squad. Kelly can activate 46 on the day of the game. To activate someone from the practice squad, someone must be released. In the past, injuries to the Eagles secondary - which is not unusual - have created just this scenario. Ditto for linebacker.

But what if you found a couple of guys from other spots to be stopgap solutions? Smart guys, athletic guys, team guys? Wouldn't you try it at least?

"It's a compliment," said Avant.

"Absolutely," agreed Harbor. "That coaches believe in you enough to think you can handle it mentally and physically. I love tight end. That's my position. I think it's the best position in football. That's my craft and it's my favorite spot on the field. But you also want to be called a football player more than a tight end or any position. When they look back on you, they can say he did special teams, you could throw him on defense if you had to. He did whatever he needed to do to help the team win."

Said Avant: "I've been inside and outside, I've been a tight end, I've been in the backfield. God blessed me with the ability to pick up things asked of me, and my coaches have done a great job tutoring me. I'm going to try my best to learn it. And if I can learn it and not mess up, coach Kelly can trust me to do other things.

"I think it's a genius mentality that you have guys prepared just in case something goes wrong. I'm a receiver: That's what I do. More than that, though, I'm a football player. So if something goes terribly wrong in a game and a lot of people get hurt they've got to put somebody over there."

At least one early review of Avant is favorable. Yesterday, safety Kurt Coleman described him as "incredibly skilled."

"He's got great feet, great hips and obviously his hands speak for themselves," said Coleman. "He can play both sides."

For Harbor, moonlighting at linebacker even provided insight that may help him with his day job.

"As a linebacker you guard tight ends," he said. "And knowing what depth and zone coverage when they drop to cover a receiver. And knowing what stance they're going to give when they go inside and then when they go outside. Knowing what stance they're giving when they're two-gapping a receiver or when they're blitzing. It really helps you as an offensive player knowing what you have to do to get open."

Avant likely is not going anywhere. Harbor knows that may not be the case for him. Rather than making him more resistant to experimentation, it has done the opposite. "I'm just trying to make myself more diverse as a player," he said. "I know there's a lot of good tight ends and I know there's a good chance I could end up going somewhere else."

If he does, he will go as a more versatile player. If he doesn't, if he stays here and even plays a little linebacker one day, well, Harbor may join those other names on Kelly's resumé, guys who were supposed to be one thing and ended up as something more.

On Twitter: @samdonnellon