ALLEN PARK -- The performance of the offensive line was arguably the biggest surprise for the Detroit Lions last season, but based on at least one offseason trend, there's reason to believe the unit could take another step forward in 2014.

Coach Jim Caldwell has been pleasantly surprised with the strength the group has added in recent months.

"Each of these guys were kind of put through the paces from a strength and conditioning standpoint, all during the spring," Caldwell said. "We take measurables at the beginning, then at the end. The improvement among the group was extraordinary."

"You can tell they're taking care of their bodies, watching what they eat, because our strength gains were great," Caldwell continued. "Guys that needed to gain a little more muscle, gained the muscle that they needed. Guys that needed to trim down a little bit, did so. It's an ongoing process, but these last few months have been incredible."

Caldwell specifically highlighted the right side of the line, where second-year pros Larry Warford and LaAdrian Waddle are the early favorites to start.

Another young lineman who impressed was Rodney Austin. After spending his first season and a half on the practice squad, he earned a promotion to the main roster late last season.

With starting left guard Rob Sims sidelined during the team portions of offseason practices, Austin has been getting reps with the first team and has caught the eye of quarterback Matthew Stafford.

"He's gotten a lot stronger, which is scary to think because he was already a strong guy," Stafford said. "He did a great job in the weight room, was here every day working hard."

In 2013, the Lions offensive line allowed just 23 sacks, the second fewest in the NFL. The added power could help the team be more effective as a run-blocking unit.

Averaging just 4.0 yards per carry, Detroit finished 22nd in the league last season. The group did manage to hold its own in short-yardage situations. The team ranked in the top five for power run conversion percentage (third and fourth down runs of two or fewer yards) both up the middle and to the right side.

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