The following is the fourth of eight position previews in advance of training camp.

OTHER POSITION PREVIEWS: Quarterbacks | Running Backs | Wide Receivers

The offensive line that steps on the field when the Bears open training camp next week will be dramatically different than the one that spent last summer in Bourbonnais.

During the offseason, the Bears moved three-time Pro Bowler Kyle Long from tackle to guard, signed veterans Bobby Massie and Ted Larsen in free agency and selected Kansas State's Cody Whitehair in the second round of the draft.

Massie joins the Bears after making 46 starts the past four seasons with the Cardinals, all at right tackle. His addition enabled Long to return to right guard, the position he played his first two seasons in Chicago in 2013-14 before moving to right tackle last year.

Long has been friends with Massie since they played high school football against each other in Virginia, has worked out with him for several years and helped recruit him to the Bears.

Larsen has appeared in 86 games with 57 starts the past six seasons with the Buccaneers and Cardinals. Having played left guard, right guard and center, the 6-2, 315-pounder provides position flexibility, which is important given that NFL teams typically have only seven linemen active on game day.

Whitehair started 52 of 53 games over four seasons at Kansas State, including a streak of 41 straight to end his career. After splitting time between left guard and right tackle his first two seasons, he started at left tackle his final two years.

Whitehair, however, is expected to begin his Bears career at guard and compete with Larsen for the starting job on the left side of the line.

"[Whitehair] is tough," Long said in May. "He's a country boy. He doesn't say much. He's here to work, here to learn. He's respectful and he's got some big, old legs, man. He's a big, strong dude. He looks like he's been bailing haystacks for a while."

After starting eight games last year as a rookie, Hroniss Grasu hopes to cement his role as the Bears' No. 1 center. The 2015 third-round pick from Oregon gained 15 pounds since the end of last season and now weighs 310. But that's not the main reason he expects to be a much better player.

"The biggest thing for me this offseason is learning the playbook even more and getting more comfortable with the playbook to where I don't even have to think anymore on the field and I can just go fast and be confident and play to my strengths, which is being fast and being quick," Grasu said in June.

"Last year I caught myself thinking too much, just thinking if I'm doing the right thing or not, if I made the right call or not. But now I've got it down."

Charles Leno Jr. Jr. returns as the Bears' starting left tackle. One of the team's most pleasant surprises last year, the 2014 seventh-round pick from Boise State was inserted into the lineup early in the season after veteran Jermon Bushrod was injured and never relinquished the position.

The Bears remain high on Leno and are confident that he will continue to develop. They also believe that left tackle is his best position and have no immediate plans to move the 6-3, 305-pounder to another spot on the line.

The swing tackle behind Leno and Massie this year could be veteran Nate Chandler. The 6-4, 306-pounder signed with the Bears June 3 after spending all of last season on injured reserve with the Carolina Panthers due to a knee injury.

"It just shows me that [the Bears] believe in me," Chandler said after he signed. "I visited with other teams and things didn't work out. But it's just a great feeling to have someone who believes in the process that I've been going through and just gave me a chance to come out here and compete."

The offensive tackle position is still relatively new to Chandler. He entered the NFL with the Panthers in 2012 as an undrafted free agent defensive end and played in 10 games on that side of the ball as a rookie, all as a reserve.

Chandler switched to offensive line in 2013, appearing in all 16 games with eight starts before starting all 11 games he played in 2014.