It's the only real mystery on the AFC champs' reloaded roster.
Their fallback plan is Wes Welker on punts and Emmanuel Sanders on kickoffs, although neither option is preferable given Welker's concussion history and Sanders' role as a starter with big plans in Peyton Manning's offense.
"If a guy can emerge as a dominant return specialist, he's going to have a pretty good opportunity to be on a roster," special teams coordinator Jeff Rodgers said.
"And if nobody emerges who's special, if Devin Hester doesn't emerge out of that group, then it's probably going to be the guy who does the best job in a combination, whether it's corner and punt return or wide receiver and punt return."
It's not like last summer when Holliday made the roster strictly as a specialist. This time, the punt and kick returners will almost certainly have to make the team in another capacity.
And that man may not even be on the Broncos' 90-man roster right now.
"If it's kind of a tie one way or the other at punt returner, it's going to be who's emerged as a wide receiver. If it's a kind of a tie as a wide receiver, it's going to be who's emerged as a punt returner as it relates to not only the wide receiver position but the corner position and well as the 3,000 guys that are on NFL rosters right now," Rodgers said.
"I know our personnel department's always looking for different guys whether it's in the building or outside the building."
The Broncos were excited about Isaiah Burse from Fresno State. He's getting a long look, but he's bobbled way too many balls without defenses even coming down on him.
Somewhat surprisingly, veteran wide receiver Jordan Norwood, who didn't play a down last season, has emerged as the steadiest punt returner so far.
Bubba Caldwell and Omar Bolden will get the chance to win the kick returner jobs during the rest of the preseason, beginning with Sunday's game at San Francisco.
Others giving it a shot are rookies Bradley Roby and Cody Latimer, both learning on the job, and running back Ronnie Hillman.