The following is the fourth installment in a series of stories that’s examining the Packers’ roster position by position. The series continues with the offensive line.

GREEN BAY – It was the best group he’s ever coached.

Now, Mike McCarthy believes the Packers’ offensive line can get even better.

Green Bay’s head coach said as much during OTAs, and none of the five returning starters expressed any disagreement. Tackles David Bakhtiari and Bryan Bulaga, guards Josh Sitton and T.J. Lang, and center Corey Linsley have always said there’s room for improvement, so they were going to challenge themselves in 2015 to improve on 2014, no matter what their coach said.

There are plenty of reasons to believe the group that blocked for Eddie Lacy’s second consecutive 1,100-yard rushing season and protected Aaron Rodgers on his way to a second MVP can indeed be better.

Both Sitton and Lang played with bothersome toe and ankle injuries, respectively, throughout the second half of last season when the offense hit its stride. Both were injured in New Orleans in Week 8, and Sitton’s toe in particular was an ongoing issue, yet the unit’s performance never suffered and Sitton earned his second career Pro Bowl selection.

Bakhtiari and Linsley are still young, ascending players who by no means have reached their peak. Thrust into emergency starting roles as rookies due to injuries, they have more than held their own and appear on their way to long careers. Bakhtiari made the transition from a promising left tackle as a rookie in 2013 to a potential franchise one last year, while Linsley will be even better versed in the offense and protection schemes in his second season this year.

Bulaga’s return with a new contract as free agency dawned was the lone maneuver needed to keep the starting five intact. He was the only one to miss a start last year – all the way back in Week 2 – and he made it through the rest of the season healthy after two years of rotten luck with injuries.

Should any health issues arise in 2015, the unit appears better equipped to compensate than a year ago. Mr. Versatility, fourth-year pro Don Barclay, is coming back from a season-ending knee injury but was doing drills in OTAs and looked on track for full duty come training camp. Most of his game experience is at tackle, but Barclay can back up any position up front.

JC Tretter is also a multi-position reserve. His knee injury in training camp last year opened the door for Linsley, and there’d be no qualms about inserting Tretter if needed, particularly at one of the three inside positions.

The unit’s depth doesn’t end there. Guard Lane Taylor has been on the active roster each of the last two seasons, while former practice-squad center Garth Gerhart moved up to the active roster last year.

They’ll be in a battle for their roster spots in what is shaping up as a highly competitive training camp. Ted Thompson did not draft an offensive lineman for the first time in his 10 drafts as Packers GM, but the unit still has plenty of young prospects.

Tackle Jeremy Vujnovich and guard Josh Walker return after a year on the practice squad to push for jobs, while all four of the four undrafted rookies coming to camp – Central Michigan center/guard Andy Phillips, Pittsburgh guard Matt Rotheram, Arizona tackle Fabbians Ebbele and Villanova tackle Vince Kowalski – were four-year starters in college.

Countdown to Camp: Position-by-position roster series