But you know what they say about stuff that doesn't kill you making you stronger.
"You can't really replicate game experience," Kelly said. "Being on film. Being able to go up against that level of intensity, that level of talent.
"I'm definitely appreciative of it. Unfortunately, I got the chance because of bad circumstances. But it was a great opportunity for me."
Kelly was the 153rd player - and 29th offensive lineman - selected in the 2012 draft. Just nine of the 28 blockers taken ahead of him started more games than he did. And eight of those nine players were taken in either the first or second rounds.
He'd love to parlay his 10 rookie starts into a starting job this season. But alas, unless there is another outbreak of ruptured tendons, torn ACLs and foot fractures, his best 2013 hope likely will be to open the season as the team's top backup at the two tackle spots.
All-Pro left tackle Jason Peters is back after missing last season with an Achilles' injury. The right tackle spot is expected to be manned by Lane Johnson, who was the fourth overall pick in last month's draft. Todd Herremans, who had been the starting right tackle before suffering a season-ending foot injury in Week 9, has moved inside to right guard.
In the early OTAs, Kelly had been taking most of the reps at right tackle with the first unit. But that was mainly because the coaching staff wanted to bring Johnson along slowly.
With Peters a no-show for the last three voluntary OTAs, Kelly has been taking snaps at left tackle with the ones, and Johnson has been lining up at right tackle.
"Just being able to get the reps with the 'ones' is good," the Purdue product said. "Getting used to what they do.
"With me going both sides, you never know what's going to happen. I've just got to do what I can do to be on the field. When [Johnson] gets his shot, we'll see what happens, and we'll go from there."
Sure, it's possible Kelly could beat out Johnson for the starting right-tackle job, but it's not very likely. Johnson has only been an offensive lineman for 3 years, which is a year less than Danny Watkins had been one when the Eagles drafted him.
But Watkins was the 23rd overall pick (in 2011). Johnson was the fourth. He would have to struggle mightily this summer to open the season on the bench. And Kelly would have to knock everybody's socks off with his play.
In other words, this won't be a fair fight when two-a-days begin in late July. Kelly knows that. Doesn't like it, but he knows it.
"It's kind of hard just because of playing so much last year," he said. "You want to come in and be considered the starter. But with him being drafted so high and being so good of a player, you kind of accept it.
"But at the same time, I want to play well and want to be seen as someone who can start here. I'm just going to take everything in stride and do what I can do."
The 6-8 Kelly was a Pillsbury Doughboy-soft 320 pounds at the end of last season. He's down to 315 now, and is leaner, stronger and quicker.
"I definitely felt I was a little sloppy by the end of the year," he said. "This weight is a lot better for me. During OTAs last year, I felt I had to pack on weight and got up to 330, but felt too slow. Now, I feel leaner and healthier. I feel I can move better at this weight and still have plenty of power."
Like every other Eagles offensive lineman, Kelly is trying to learn a new system and new blocking schemes and getting adjusted to a new position coach, Jeff Stoutland.
"It's a little easier because of my familiarity with zone [blocking] schemes from last year and in college," he said. "But it's a little difficult in that you're used to the old playbook and now you've got to learn a completely new one, with all the new terms and new [blocking] technique. But everyone's going through that. So we're all learning at the same pace."
Kelly spent his rookie season being tutored by Howard Mudd, who had been an NFL assistant for nearly 40 years. Mudd has been replaced by Stoutland, who has spent his entire career as a college assistant.
" 'Stout' is a lot different than Howard," Kelly said. "Very high intensity. Attention to detail. Doesn't leave anything uncovered. He wants to make sure whatever situation happens, we're ready for it. I like that approach. He hates gray areas, which, as an offensive lineman, happens a lot."
Stoutland spent the last 2 years as the offensive-line coach at Alabama. While Chip Kelly's offense will feature many of the same zone-blocking schemes that Andy Reid's did, they will be a lot more power-based than they were under Reid and Mudd.
"Obviously, [Stoutland] has brought some of the techniques from Alabama, and they were definitely a downhill, attack team, whereas Howard was more of a speed guy," Kelly said. "Jeff likes to have the physical aspect in it. Smack the guy in the mouth and move him backwards."
So far, Stoutland has been impressed by what he's seen of Kelly in the padless OTAs.
"He might've had just one day where he didn't perform better than the day before," Stoutland said late last week. "He's gotten better every day. He's done some nice things the last couple of days. I'm happy with him."
On Twitter: @Pdomo