ENGLEWOOD, Colo. -- Tight ends Jake Butt and Jeff Heuerman and quarterback Chad Kelly all missed their rookie seasons because of injury.

“For those guys, like a lot of guys, it’s about getting healthy," Broncos coach Vance Joseph said. “It’s about getting your body right so you can compete, show what you can do."

Butt, who was drafted in 2017, was recovering from a knee injury suffered in his final game Michigan. Kelly, who was in the same draft class, injured his knee at Ole Miss. He also injured his wrist in a pre-draft workout. Heuerman, now in his third season on the roster, missed his rookie year after he suffered a torn ACL in a Broncos rookie minicamp days after he was selected in third round of the 2015 draft.

Heuerman’s injury, as well as Dante Fowler Jr.’s in Jacksonville that same offseason, had a significant impact on how teams have since conducted their rookie minicamps. The Broncos, like many teams, now emphasize classroom work over on-field practices.

But all three of the players know the day-to-day tedium of injury recovery as a season goes on around them, they know the uncertainty of wondering what their standing will be when they are healthy enough to return. They know waiting really is the hardest part.

“You see everybody practicing every day, the games, and you’re just trying to concentrate on recovering," Kelly said. “You’re working and working, just not for Sunday that week."

Heuerman’s recovery seemed to linger into the 2016 season as he battled other injuries that resulted in missed practice time. He finished his second “rookie’’ year with nine receptions in limited time in 12 games.

Then 2017 wasn’t much better, another nine-reception season as he played an average of just 23 snaps in his 14 games. There was concern early in training camp this summer when Heuerman missed time with a sore knee, but he has flashed some quality work in preseason games as the most experienced player at the position.

“We’ve always had expectations for him because we feel like he has a lot of talent," Broncos president of football operations/general manager John Elway said. “He’s always wanted to be out there and wants to be a good player. He just needs to stay healthy and we just need to keep him on the field."

Butt has yet to be in uniform for a regular-season game, but the Broncos see him as a potential starter in some of their long-yardage situations as well as a red zone target given his 6-foot-6, 250-pound frame. Joseph has framed Heuerman and Butt as co-starters of sorts, depending where the offense is on the field.

“They’re different," Joseph said. “As having a No. 1 tight end for our offense, not that important, but having a couple guys who can do different skill sets is more important for us. It’s no different than having more than one [running] back. Heuerman is a bigger man, he’s more of an inline blocker for us, and Butt is a pass-catcher, a route-runner, a guy who can play in space vs. ’backers and win."

Kelly may have covered the most ground from the start of his recovery to his current standing. While he doesn’t figure to play much in the coming season, he has lifted himself from a wait-and-see, last-pick-of-the-2017-draft prospect into the conversation as Case Keenum’s backup, having beaten out a former No. 1 pick in Paxton Lynch.

“I’m never satisfied with what I’ve done and I think even the great ones feel the same exact way," Kelly said this week. “There’s so much more I can learn and build off of, and I’m going to keep striving each and every day to get better than the day before. I think good things will happen as long as you keep an edge in your mind and keep working hard."

Said Joseph: “They all worked to get where they are. We’ve been smart in our approach with them and the training staff. And we’ve seen the benefits and hopefully we continue to see those benefits."