Last season, New York Giants running back Saquon Barkley took the NFL by storm in his first season, leading the league in yards from scrimmage (2,028) while averaging a robust five yards per carry.
That wasn't entirely unexpected. Selected No. 2 overall in the NFL Draft by a team with a clear need at the position, Barkley had both the pedigree (3,843 yards rushing, 43 touchdowns in three seasons at Penn State) and situation to excel as a rookie.
Colts linebacker Darius Leonard arrived with less fanfare, as a second-round pick out of tiny South Carolina State. But, the results were comparable: A league-leading 163 tackles (including an NFL-high 111 solos) to go with seven sacks, 12 tackles for loss, four forced fumbles and eight pass breakups.
Barkley and Leonard were the NFL's rookies of the year on offense and defense, respectively.
Who could be the next Barkley or Leonard? Who knows, until the season begins. But, here's five rookies worth tracking, both because of their skill and opportunity.
Josh Allen, DE/LB, Jacksonville Jaguars
The Jaguars already boasted a top-five defense from a year ago, yielding just 311.4 yards per game (fifth), and 19.8 points (tied for fourth), so adding the former Kentucky pass rusher to the mix is a scary proposition for opponents.
Allen collected 17 sacks and 21.5 tackles for loss in his final year in college before Jacksonville scooped him up with the No. 7 overall pick. He has five tackles in limited time this preseason, and has fit in nicely with a defense that already features Calais Campbell, Yannick Ngakoue and Marcell Dareus along the front line.
Devin Bush, LB, Pittsburgh Steelers
The Steelers moved up 10 spots in the NFL Draft to select the former Michigan star at No. 10 overall as the replacement for inside linebacker Ryan Shazier, who suffered a spinal injury two seasons ago.
Bush has been as advertised with 18 tackles over three starts this preseason, and solidifying himself as an early favorite for defensive rookie of the year honors.
Josh Jacobs, RB, Oakland Raiders
Jacobs was the first running back selected in the NFL Draft, at No. 24, and already figures to be the workhorse in the Raiders' backfield, with the team recently cutting ties with Doug Martin, last season's leading rusher.
Jacobs split backfield duties in his final season at Alabama, rushing for just 640 yards, though they came at a 5.3 yards-per-carry clip, and included 11 touchdowns. He also was an effective receiver with 20 catches for 247 yards and three more touchdowns.
He'll have an opportunity to put all of those skills to work in an offense that also has added receivers Antonio Brown (Central Michigan), Tyrell Williams and fellow rookie Hunter Renfrow.
Kyler Murray, QB, Arizona Cardinals
Of all of the rookies, Murray is the most obvious, and likely to be the most heavily scrutinized. The No. 1 overall pick, Murray is all but ticketed to be the Cardinals' Week 1 starter, piloting a new spread offense from new head coach Kliff Kingsbury.
Murray brings plenty to Arizona as a Heisman Trophy winner (which is no guarantee for success) with dual-threat abilities (he was a 1,000-yard rusher in his final season at Oklahoma) that might help offset concerns over his 5-foot-10 frame.
And, though the Cardinals won just three games last season, the cupboard isn't necessarily bare on offense. David Johnson is one of the NFL's most versatile running backs, and Murray will throw to efficient (and aging) Larry Fitzgerald, as well as up-and-comer Christian Kirk.
Miles Sanders, RB, Philadelphia Eagles
In March, the Eagles acquired Jordan Howard in a trade with the Bears, with Howard pegged by some to lead a crowded backfield in Philadelphia. Sanders, however, has added his name to the mix during an impressive preseason.
Drafted No. 53 overall, Sanders rushed for 31 yards on five carries in the Eagles' second preseason game against the Jaguars, showing both power and elusiveness he displayed while at Penn State.
With Howard, veteran Darren Sproles and Corey Clement all in the mix, Sanders might have to wait for an opportunity, but he appears up to the challenge.