In 2015, the Chicago Bears ran the ball 469 times, which was sixth most in the NFL. Of those 469 runs, 179 (38 percent) were run behind the guards.
The Bears ran 105 times behind right guard, more than any other team in the league, while the club's 74 runs behind left guard were second most in the NFL.
For a run-heavy team looking to build on that approach in 2016, Chicago's guards, along with the center position, will play a major role in the success of the rushing attack. In addition, they'll also be tasked with keeping interior defenders out of Jay Cutler's face.
Yet the Bears have made significant changes up front, which started with the head-scratching dismissal of Matt Slauson, the club's starting left guard the past three seasons. The club also moved a Pro Bowler from tackle to guard and then drafted a second-round guard.
The Bears also signed two interior blockers in free agency, although Manny Ramirez retired a month later.
With that in mind, let's break down the guards and centers who will be competing during Bears 2016 Training Camp.
After two Pro Bowl seasons at guard, the Bears moved Kyle Long to right tackle last year. The results were spotty, although he did improve as the season wore on.
On the right edge, Long gave up 28 QB hurries, 3 QB hits and 6 sacks (Slauson played one less snap than Long and allowed just 9 hurries, 1 hit and 2 sacks, but hey, who's counting?).
Those types of pressure numbers were somewhat surprising from Long, who was a rock in pass protection at right guard the previous two years.
After the team signed OT Bobby Massie in free agency, Long was shifted back to right guard. More than any move the Bears made in free agency or the draft, moving Long back inside will have the biggest impact for Chicago's offensive line.
Long is arguably the most athletic offensive lineman in the league. He's 328 pounds but moves like a player 100 pounds lighter. He has outstanding balance and wicked power at the point of attack, and understands how to use leverage and body angles to his advantage.
Long's presence at right guard - alongside Massie, who is a plus run blocker - should pay big dividends in the run game. The Bears should be able to run to the right side very effectively this year.
Yet Long will also stabilize the interior on passing downs. Vladimir Ducasse and Patrick Omameh struggled mightily in pass protection last year, so getting Long back at right guard should help keep Cutler clean.
The Bears traded back twice in the second round of the 2016 NFL Draft to select Cody Whitehair out of Kansas State. He played left tackle collegiately but, due in large part to his 32 3/8-inch arms, he'll slide inside to guard for the Bears.
During OTAs, Whitehair worked at left guard with the second team but moved into the starting lineup during veteran minicamp. The Bears believe he's a Day 1 starter.
"He’s an aggressive player. He’s really good in space," GM Ryan Pace said after drafting Whitehair. "He plays with great inside hand placement and he’s got strong hands. I love offensive lineman with strong inside hands. When they latched on you can’t get rid of him. He’s a very difficult player to shed once he gets his hands on your chest."
On film, Whitehair shows very good technique and decent athleticism. He moves well down the line and has solid awareness at the second level.
Whitehair has the ability to sink his hips and drive defenders out of the hole, which should help the offense in short-yardage situations.
The Bears have some competition for Whitehair but if he performs to expectations during training camp and the preseason, he'll easily emerge as the team's Week 1 starter at left guard.
The Bears invested a third-round pick on Hroniss Grasu in last year's draft, yet the rookie struggled in the preseason, showing a disturbing lack of power after the snap.
As a result, Grasu was a healthy scratch for the first four weeks of the season, yet he was thrust into the starting center role after Will Montgomery broke his leg.
Grasu was not ready to be a starter last year and it showed on the field. He struggled mightily in his first game against the Chiefs, which forced the coaching staff to alter their protection schemes in order to give Grasu help inside. That left the tackles on an island most snaps.
Grasu must improve at the point of attack. He must better utilized leverage and angles of attack, while learning how to coil his hips and create push. He gained 10 pounds this off-season, which is a great start, but it won't mean anything if his technique continues to wane in the run game.
At the second level, Grasu is very good. He's extremely agile and quick, and gets down the line in a hurry on pulls and traps. His movement ability is by far his strongest asset.
In pass protection, Grasu must anticipate better and not allow defenders to get under his pads. He also must find a way to better anchor against bull rushers.
Grasu is penciled in as the starter but he's still a work in progress in every phase of the game. He'll need to show significant improvement this season, otherwise he'll again serve as Chicago's weak link up front.
Larsen is a six-year NFL veteran who spent the last two seasons with the Arizona Cardinals. Pro Football Focus graded Larsen 77th out of 82 qualifying guards last season in terms of overall play.
He was essentially the sixth worst guard in the NFL last year, yet the Bears signed Larsen to a one-year deal with a base salary of $1.65 million and incentives that could net him a max deal of $2.4 million. You don't pay that much money to an interior offensive lineman unless you believe he has starter potential.
Larsen has started 57 of 86 career games played, at both guard and center. So even if he loses the starting gig to Whitehair, Larsen provides very good value as a swing guard and backup center, where he can step in immediately if Grasu falters.
Larsen took first-team reps at left guard during OTAs but sat out veteran minicamp due to an undisclosed injury.
Edison (6-3, 309) was signed to the Bears practice squad on Nov. 30 last year and earned an invite to training camp this season.
An undrafted free agent out of Portland State, Edison was the Rimington Award winner in his senior year in 2014, given to the nation's top center.
With Grasu and Larsen ahead of him, Edison will need to be outstanding over the next two months if he's going to claim a roster spot. If not, he's a prime candidate for another season on the practice squad.
Wallace enters his fourth NFL season after entering the league as an undrafted free agent in 2013. Over the past three years, he's played for the Brown, Buccaneers and Panthers, and was signed to the Bears practice squad in November last year.
He's been active for just one game during his career, which came during his rookie season in Cleveland. He has very good size (6-6, 330) but he's buried on the depth chart and worked exclusively at left guard with the third team during OTAs and minicamp.
If he can harness his size and experience, there's an outside chance Wallace could compete for the swing guard spot.
Williams is an undrafted free agent out of Lousiana Lafayette. A JUCO transfer, Williams played both guard and center in college.
The 6-3, 315 pounder played right guard with the third team during off-season activities and will battle in training camp for a spot on the practice squad.