This is the fourth in a series of stories that's examining the Packers' roster, position by position, heading into training camp. The series continues with the offensive line.

GREEN BAY – The offseason program provided some clarity on one uncertain spot on the Packers' offensive line, but it remains wait-and-see on the other.

Justin McCray appeared to establish himself as the front-runner for the open starting job at right guard. A super-sub last season who started a total of eight games at three different positions, McCray made himself an invaluable member of the unit and now could be getting a shot as a full-time starter for the first time.

Undrafted in 2014 and playing in the Arena League with his twin brother in 2016, McCray has seized every opportunity the Packers have given him thus far.

He'll still have to earn the gig, though, because fellow undrafted linemate Lucas Patrick will be vying for it, too, after playing all but the opening snap of the last two games in 2017.

Don't rule out veteran free-agent pickup Byron Bell, either, who has started at three different positions in his career. The majority of his 74 career starts with the Titans, Panthers and Cowboys have come at right tackle (48), but the Packers showed interest in Bell on the free-agent market last year before signing Jahri Evans to play right guard.

In addition, rookie fifth-round draft pick Cole Madison will be in the mix as he converts to guard from playing tackle at Washington State, and 2016 sixth-round pick Kofi Amichia, who spent all of his rookie season on the practice squad, could make a push as well. Ethan Cooper was a recent addition at guard via the waiver wire.

Right tackle isn't as well understood, though, because the status of veteran starter Bryan Bulaga won't be known until the start of camp at the earliest. Bulaga is coming off ACL surgery from an early November injury, and while all reports on his recovery and rehab have been positive, no date has been announced on when he might get full medical clearance.

If Bulaga isn't ready for Week 1, the preseason will feature an intriguing battle for the starting spot. Two draft picks from 2016, Jason Spriggs (second round) and Kyle Murphy (sixth) both have game experience in their young careers but are coming off injuries of their own.

Spriggs built up his body in the offseason while working back from a knee injury, and Murphy was cleared for full 11-on-11 work toward the end of OTAs following his foot injury from 2017.

Bell is a candidate here as well, while the undrafted rookie added to the tackle group this year is Richmond's Alex Light. He, along with practice-squad holdover Adam Pankey, is listed at both tackle and guard.

The left side of the line is the one the Packers have locked down, of course, with two-time All-Pro David Bakhtiari at left tackle and two-year starter Lane Taylor at left guard.

Bakhtiari missed four early-season games a year ago due to a significant hamstring injury but otherwise missed only two games in his first four years as a starter. Taylor has missed just one game since taking over for the departed Josh Sitton in 2016.

Corey Linsley is entrenched at center, of course, and he's coming off his first healthy offseason in a couple years following a December contract extension.

Late-season acquisition Dillon Day and undrafted rookie Austin Davis, a former teammate of Patrick's at Duke, are his listed backups, though McCray and Patrick have taken practice reps at center in the past as well.