Football is a symmetrical game. It works best, at most position groups, when two players operate in concert.
With the best pairings in the sport, one player makes the other better. Here's a look at our choices for the top college tandems in 2017:
Running back: Nick Chubb and Sony Michel, Georgia
The most productive returning pair in career output with 5,835 yards over the past three seasons, Chubb and Michel don't necessarily provide the change of pace that traditionally effective tandems feature.
Not that it matters. In the rough-and-tumble SEC, both big-bodied backs are capable of pounding the line of scrimmage and pulling away from the secondary -- evidenced by Chubb's breakout freshman season in 2014 and Michel's best year to date in 2015.
Chubb has battled back from a severe knee injury, and Michel overcame a gruesome, offseason arm fracture a year ago. Perhaps their best attribute? An unwavering team-first attitude that has allowed both to thrive after arriving at Georgia together as top-100 prospects.
"They have great passion for the game," Georgia running backs coach Dell McGee said, "and they definitely have a great friendship. They push each other on the football field, in the weight room and in the classroom. They're a great example to our whole team."
Chubb and Michel announced on the same day in mid-December last year that they would return as seniors in 2017.
"In a day and age when everything in football is all about me, me, me, these two guys have never been like that," Georgia coach Kirby Smart told reporters after the Bulldogs' victory over TCU in the AutoZone Liberty Bowl. "They're not 'me' guys."
The next best
Myles Gaskin and Lavon Coleman, Washington
A true thunder-and-lightning duo, with the smaller Gaskin rushing for 62 percent of their combined 2,225 yards last season -- the No. 2 returning total nationally behind Western Michigan's Jamauri Bogan and Jarvion Franklin.
Bo Scarbrough and Damien Harris, Alabama
Scarbrough's impression of a freight train in the CFP semifinal is still causing sleepless nights in Seattle. Harris topped 1,000 yards last year and ranked as the No. 2 running back prospect in the recruiting class of 2015.
Wide receiver: James Washington and Jalen McCleskey, Oklahoma State
The Cowboys are loaded at wideout, forming a lethal mix with Heisman-hopeful quarterback Mason Rudolph that could land Oklahoma State in the thick of the College Football Playoff race.
Talk to three observers high on coach Mike Gundy's team in 2017 and you might hear three names other than Washington and McCleskey at receiver who are generating the most excitement.
Reality is, despite the emergence of LSU transfer Tyron Johnson, the return from injury of Marcell Ateman and the continued development of Chris Lacy, the senior Washington -- a Biletnikoff Award front-runner -- and the junior McCleskey are likely to remain as Rudolph's top targets.
"We want to try to get the ball to Jalen first," Oklahoma State receivers coach Kasey Dunn said. "And then as soon as the safeties start to drop down on top of him, that's when we start to take advantage with James.
"When he sees one-on-one coverage, we want to get him the ball, because he's so good on any 50-50 ball."
McCleskey's 73 catches (for 812 yards) ranks as the top returning total in the Big 12, and Washington snagged 71 balls last year for 1,380 yards, the third-highest total among returning FBS receivers.
Washington possesses an NFL body and plays bigger than his 6-foot, 205-pound frame. Strong hands help him win most battles and place Washington above all returning FBS players with 26 career receiving touchdowns.
McCleskey is a speedster, the son of former NFL defensive back Tommy McCleskey. He's also a special-teams standout whose skill set may have been only lightly tapped last year en route to his 812 receiving yards.
The next best
Devin Ross and Shay Fields, Colorado
Life without Sefo Liufau could hurt the productivity of this senior duo, but their talent is beyond question after Ross earned first-team All-Pac-12 honors, and Fields actually outgained him with 883 receiving yards in 2016.
Nick Westbrook and Simmie Cobbs Jr., Indiana
On the heels of a 1,000-yard sophomore season, Cobbs went down with an ankle injury in the 2016 opener, making way for Westbrook, who nearly matched his numbers. The two juniors on the field together create trouble with their size.
Offensive tackle: Orlando Brown and Bobby Evans, Oklahoma
Charged with the all-important task of ensuring Baker Mayfield's safety in the pocket, Brown at left tackle and Evans on the right side form a bookend duo that allowed the Sooners to rank No. 1 nationally in QBR, No. 2 in yards per game, No. 3 in yards per pass attempt and No. 4 in third-down conversion rate.
The Bob Stoops retirement aside, that's the kind of uniformity that Oklahoma seeks in 2017 as it bids to extend an FBS-high, 10-game winning streak.
A second-team All-American as a redshirt sophomore in 2016, Brown, 6-8 and 360 pounds, played 659 snaps and allowed one sack. He opted to bypass the NFL draft, but it might not be so easy to make the same choice after this season. If he leaves, Brown appears in position to end the Sooners' drought at five years without a first-round pick.
The 6-4, 316-pound Evans joined Brown in the lineup for the final 12 games last year as a redshirt freshman, showing the kind of athleticism that earned his dad, Bobby Joe Evans, a basketball scholarship to OU in the 1990s and his brother, Tay Evans, three starts at linebacker before concussions ended his Oklahoma career.
"Individually, they're both really good players," new OU coach Lincoln Riley said. "Orlando has gone from becoming a really good player to a dominant player. He's got one of the most elite mentalities of any player that I've coached. He's a dream offensive lineman with his competitiveness and his nasty streak, his attitude and the chip on his shoulder."
Evans' readiness also pushed Dru Samia inside, solidifying one of the nation's top offensive lines.
The next best
Jamarco Jones and Isaiah Prince Jr., Ohio State
Experienced and blessed with size and elite talent, Jones and Prince return to their starting spots from 2016. A two-year starter on the left side, Jones anchored the group that last year finished among three finalists for the Joe Moore Award for the most outstanding offensive line of the year .
Tyler Howell and Paul Adams, Missouri
Out of nowhere, this Mizzou duo emerged last year to start every game and pace the Tigers' dramatic improvement. Missouri allowed an FBS-low 36 tackles for loss last year, down from 88 in 2015.
Defensive end: Tyquan Lewis and Sam Hubbard, Ohio State
If you need another reason to count the days until Sept. 9, when Oklahoma visits Ohio State, consider the matchup between the Sooners' aforementioned offensive tackles and this menacing tandem.
Lewis and Hubbard were a force off the edge last year as part of the No. 6 defense nationally, measured by yards per game. They combined for 11.5 sacks, sharing time with backups Jalyn Holmes and Nick Bosa -- who would start on nearly any other team and also form a feared duo.
Yes, the Buckeyes feature an embarrassment of riches at the pass-rushing positions. If Ohio State had only Lewis and Hubbard, though, well, it would still rate as the best.
In some aspects, they are interchangeable.
"The issue that teams face," Ohio State defensive line coach Larry Johnson said, "is, 'Who are you going to to turn your attention to?' Somebody is going to have one-on-one. We're looking for matchups. We try to create matchups. With those two -- and with rotating the others -- it really creates a nightmare, because you can't get a bead on where they're coming from."
A 6-4, 265-pound senior, Lewis was named the Big Ten's top defensive lineman last season and needs 11 sacks to finish second in Ohio State history behind Mike Vrabel.
Hubbard, at 6-5 and 265 pounds, broke into the lineup last season after playing a key backup role on the Buckeyes' national championship team in 2015. He's a former high school safety and an academic All-American.
Interestingly, neither defender came to Columbus with much hype, relative to many of their teammates. They're both self-made stars, a useful attribute at a position that requires maximum effort when lined up every play opposite the biggest men on the field.
"They're great leaders and great workers," Johnson said. "That is the epitome of what you're looking for in defensive ends."
Josh Sweat and Brian Burns, Florida State
The Seminoles lose DeMarcus Walker but might be better, somehow, off the edge if Sweat and Burns come of age. Sweat is a former five-star prospect who showed his skills in the second half of last season, and Burns led all freshmen nationally with 9.5 sacks in 2016.
Cornerback: Trevon Diggs and Anthony Averett, Alabama
Just pick your Alabama pair. The Crimson Tide's secondary ranks as the best in the SEC and among the best nationally. Heading into August practices, Diggs and Averett look like the top duo at corner, but if junior Minkah Fitzpatrick -- arguably the top defensive back in the nation -- or senior Tony Brown starts at corner on Sept. 2 against Florida State, it would come as no great surprise.
In Diggs and Averett, Alabama has a pair of former ESPN 300 prospects who have taken winding paths -- much shorter for Diggs than Averett -- to this spot. Diggs, the brother of Minnesota Vikings receiver Stefon Diggs, arrived in Tuscaloosa last year, playing safety and wide receiver before he settled at corner in the spring.
His progress allowed the Crimson Tide to move Fitzpatrick back to safety, where he earned All-America honors last year after taking over for the injured Eddie Jackson. That Alabama coaches made that decision with Fitzpatrick, a natural corner, speaks to their confidence in Diggs.
"I feel like he picked it up quicker than I did," Averett told reporters in the spring.
Averett, in fact, did not play a meaningful snap on defense until last season, when he started the final 14 games and led the team in pass breakups as a regular target of quarterbacks opposite eventual first-round pick Marlon Humphrey.
Averett collected 48 tackles and answered every question -- that is, until the College Football Playoff title game, when Deshaun Watson finally got the best of Bama's seemingly unbeatable defense.
No matter if the combination at corner includes Fitzpatrick or Brown, another former five-star signee and key contributor last season, Alabama appears prepared to lock down.
For now, the jobs belong to Diggs and Averett.
The next best:
Iman Marshall and Jack Jones, USC
Another high-talent combo, led by a veteran in Marshall, the former No. 1 corner prospect nationally who thrived last year opposite Adoree' Jackson. Jones emerged last year as a freshman and enters preseason camp with the inside track to start.
Jaire Alexander and Trumaine Washington, Louisville
Alexander, a second-team All-ACC pick last year who led the Cardinals with five interceptions, opens this year as an All-America candidate. If the senior Washington returns to 2015 form, this duo clearly rates as the best in the ACC.