ENGLEWOOD, Colo. -- The Denver Broncos were already crowded at running back.

They already had three players in Phillip Lindsay, Royce Freeman and Devontae Booker who had each taken plenty of snaps with the starters during training camp, and coach Vic Fangio had said each could be used at any time, in any situation.

They were already a headache for fantasy football aficionados. And then the Broncos added Theo Riddick.

Suddenly it's Riddick who has played more NFL games (84), has more career carries (288) and more receptions than any back on the Broncos' roster. Riddick, who played a handful of plays in the preseason loss in Seattle Thursday night, is the only Broncos player who has caught at least 50 passes in each of the last four seasons -- Emmanuel Sanders had 47 catches in 2017, breaking his string of 50-catch seasons.

"Right now he's going to get thrown in the mix," Fangio said. "He's had a good history in his career of being a good receiver out of the backfield and a good threat in that way. Obviously, we'll see if we can fit him in that way, and if he still has that going for him. He's been a good receiver. I've seen him play the last four years in the same division."

Lindsay and Freeman still figure to get most of the work in the running game by the time the Broncos dive into the regular season in September. But Riddick's arrival does stir things up a bit at a position group where the Broncos kept three players, in addition to fullback Andy Janovich, when they cut the roster to 53 players in 2018.

They did keep four running backs, in addition to a fullback, to open the season in 2017, but they also kept three in 2016 and 2015. Thursday night's game against the Seattle Seahawks offered a glimpse of how the Broncos already see Riddick in their offense. He was targeted twice in the passing game in limited work and he showed himself to be a quick study in the offense as well as an on-point route runner.

If the Broncos are unwilling to keep more than three backs or do not waver from their usual split of 25 players on offense, 25 players on defense to go with the kicker, punter and long-snapper when they cut to 53, the preseason could shape up to be a Riddick or Booker decision. If they keep four, the question then becomes whether they have enough work to spread around to make it worthy of that extra roster spot.

But hold that thought, Fangio says at the moment.

"I don't know if it puts any more pressure on any one guy," Fangio said. "Obviously when you add a quality player to a group it's to be noticed. When it comes down to picking the final team it's fluid. It's pretty etched in stone you have to have these 40 guys -- meaning position-wise -- how many numbers at a position, and your last 10, 13 guys is based upon fit and ability and future and all that."

Riddick's ability as a receiver certainly fits the profile in the team's new offense because the backs are going to be involved catching the ball. Riddick has four 50-catch seasons, including 80 catches in 2015. With the run of injuries at tight end already in training camp, including Jake Butt's knee troubles as well as rookie Austin Fort's torn ACL against the Seahawks, the Broncos' backs could all be more involved in the passing game once the regular season begins as well.

Riddick has also played for current Broncos running backs coach Curtis Modkins before -- from 2013-2015, when they were with the Detroit Lions. Riddick, who had been a free agent after he was released by the Lions in late July and had also visited the New Orleans Saints, believed his best chance to stick was in Denver.

"Because they are going to utilize my talent and my strengths," Riddick said. "I have a lot of experience being in the game for six years. We got a young room -- very talented, but hopefully I can help them out in terms of things they can see before it happens. You only can get that from experience, so hopefully it comes in handy."

In his first days of practice, Riddick was tossed into things quickly as he and Booker had already appeared in the same backfield in some of the team drills.

"I think there's a versatility there," Riddick said. " ... You just want to be able to do whatever they need you to do, take some stress off other guys. I just want to show these coaches what I can do and just fit."