ENGLEWOOD, Colo. -- In the hours after the Denver Broncos closed out the NFL draft by selecting quarterback Chad Kelly with the last pick of the three-day affair, the team's football decision-maker, John Elway, had a bit of a prediction about the team's newest class of rookies.

"I like this group," Elway said at the time. "I like our roster and we don't have that much room, but I think this group could get in there and have some impact."

Most teams' personnel executives say similar things in the aftermath of draft weekend, but the Broncos' rookie class has some players who have already worked their way into the mix heading into their first preseason game.

Start with wide receiver Isaiah McKenzie, who technically became the first rookie to earn a starting job when coach Vance Joseph declared him the team's punt returner before McKenzie had actually caught a punt in an NFL game. But the fifth-round pick is a speedster who's made it clear in training camp thus far that he is the best player for the job.

That's barring a total meltdown in the four preseason games starting with Thursday night's opener in Chicago, as Joseph has already said McKenzie would return punts in the Sept. 11 regular-season opener against the Los Angeles Chargers.

"We vetted him throughout training camp; he's done a good job of catching the ball, he's a very confident young man," Broncos special teams coordinator Brock Olivo said. "... Both Vance [Joseph] and I decided, 'Let's throw him in the fire, let's see what he's made of.' Obviously he hasn't caught a punt in a game yet and that's a whole different animal, but we've got to see what the kid is made of, so we're going to roll with him."

First-round pick Garett Bolles hasn't been officially awarded the left tackle job but seems well on his way, having taken plenty of snaps with the starters throughout training camp. Bolles will also be in the starting lineup against the Bears on Thursday.

He was formally listed as a starter on the first depth chart the Broncos released this past week, but Bolles said he'll believe it when he lines up against the Chargers and not before then -- that until Week 1, "it's a name on a piece of paper."

Also, with the injuries the Broncos have had at outside linebacker -- both Shane Ray (wrist) and Shaquil Barrett (hip) are not expected back in the lineup until after the start of the regular season -- DeMarcus Walker has gone from a second-round pick the Broncos believed could play at defensive end and defensive tackle in some pass-rush situations to now also playing outside linebacker.

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Walker has worked plenty at outside linebacker in recent practices, and the Broncos would like to see how he handles the additional responsibilities against the Bears. Linebacker Von Miller has helped Walker along the way and has said Walker "can play linebacker, no doubt."

"It's whatever the coaches want me to do, to be honest with you," Walker said. "I'm just here to help try win a Super Bowl, so whatever Coach Joseph or Coach [Joe] Woods wants me to do, I'll do it."

Because Jamaal Charles will not play against the Bears and Devontae Booker is still recovering from surgery to repair a fractured bone in his left wrist, fifth-round pick De'Angelo Henderson is expected to get a selection of snaps at running back.

Henderson has flashed plenty of speed and decisiveness with the ball as he pushes hard to force the Broncos to keep an extra running back when the roster goes to 53 players. Wide receiver Carlos Henderson (third round) and cornerback Brendan Langley (third round) could see the field as early as the second quarter, too.

Langley is pushing to be the team's fourth cornerback -- he was listed ahead of Lorenzo Doss on the depth chart earlier this week, but Joseph said that decision is far from made.