Broncos rookie wide receivers Carlos Henderson and Isaiah McKenzie, along with fellow rookie running back De’Angelo Henderson, have all generated buzz as they are expected to bring explosive playmaking to a Broncos offense and special teams unit that lacked it last season.

But looking at the past performance of some of the rookies at their positions over the last five years, success will not be easy. That is not a knock on the talent of the rookies. Rather, it’s a reminder that the leap from college to professional football is not an easy one. Here’s a look at some of the most noteworthy rookie performances from Broncos rookie running backs and wide receivers since John Elway joined the front office, and what it could mean for this year’s crop.

Ronnie Hillman – Running Back (3rd Round, 2012)

Hillman’s rookie stat line was uninspiring. He translated 85 carries into 335 yards (3.9 yards per carry) and one touchdown. Viewed more as a change-of-pace back who can help in the passing game, Hillman’s receiving contributions were just as limited. He caught 10 balls for 62 yards and one touchdown in 14 games. Hillman found himself behind Knowshon Moreno and Wills McGahee on the depth chart and was never able to establish himself as a starting back.

Montee Ball – Running Back (2nd Round, 2013)

When Ball came to the Broncos in 2013, he was given a real chance to succeed. The only running back ahead of him on the team’s Week 1 depth chart was the aforementioned Hillman. Despite Hillman not living up to expectations, Ball was unable to run away with the job as Moreno eventually surpassed him as the team’s leading rusher. Though he did have a promising rookie campaign, Ball flopped the following year before being cut in advance of his third season.

Tavarres King – Wide Receiver (5th Round, 2013)

What do Tavarres King and Isaiah McKenzie have in common? They are both wide receivers from the University of Georgia who led the Bulldogs in receptions, receiving yards and receiving touchdowns in their junior season before being selected in the fifth round by the Broncos. Though King is bigger than McKenzie, they both used their quickness and speed off the line of scrimmage to create space in college. King was ultimately cut by the Broncos in Week 7 of the 2013 season without seeing any appreciable playing time in Denver. Throughout his NFL career, King has just four receptions for 63 yards.

Cody Latimer – Wide Receiver (2nd Round, 2014)

Latimer was drafted as a hopeful contributor in a crowded Broncos receiving corps that featured Demaryius Thomas, Emmanuel Sanders and Wes Welker. Latimer’s tangibles are more than tantalizing; measuring 6-foot-2-inches and 215 pounds with 4.4 speed, Latimer was labeled a “height/weight/speed specimen” by Mike Mayock coming out of Indiana. What’s more, he had time to develop behind three Pro Bowl receivers and play with an all-time great in Peyton Manning. Unfortunately for Latimer and the Broncos, that development has been nonexistent. Over three professional years, Latimer has accumulated just 158 yards and one touchdown. Now entering his fourth season, Latimer finds himself fighting for a roster spot.

Devontae Booker – Running Back (4th round, 2016)

Of all the players on this list, Booker had the most successful rookie season. He led the Broncos in rushing with 612 yards on 174 attempts. However, much of this came as a result of necessity rather than his seizing the job. Incumbent starter C.J. Anderson played just seven games due to injury, and Booker was the next best option. His 3.5 yards per carry ranked last among Broncos running backs and he led all rushers with four fumbles. Booker’s rookie success goes to show that opportunity can at times outweigh talent.

The 2017 Crop

So what does all of this mean? It doesn’t cause reason for excitement in regards to McKenzie (5th Round) and the Hendersons (Carlos 3rd Round, De’Angelo 6th Round). Even when players figure to have the skills and opportunity to succeed, like Ball and Latimer, that was not the case. They proved that a transition from college football to the NFL is a daunting task.

Booker, the lone player to have success his rookie year, did so due mostly to opportunity. For the 2017 backs and receivers, that opportunity could be difficult to come by.

At receiver, Carlos Henderson and McKenzie figure to begin training camp behind a number of veteran players. The backfield is just as crowded, as De’Angelo Henderson has at least three names to leapfrog on the depth chart.

Though the talent could undoubtedly be there, but the roster ahead of them may be simply too crowded for the rookies to make an impact at their position in year one.