July 24, 2014 at 1:00 am

Lions training camp position previews: Offensive line

This is the fourth in a series of position previews in advance of Lions training camp. Today: Offensive line. See the roster breakdown in the gallery above or by clicking here .

Allen Park — The Lions’ offensive line was one of the biggest question marks entering last season, but after giving up the second fewest sacks, it looks like a point of strength this year. The group returns all of its top starters and has a good mix of veteran and young depth.

The key battle during training camp will be right tackle, where eight-year veteran Corey Hilliard, who started seven games last year, will compete with second-year LaAdrian Waddle, who started eight as a rookie.

And while center Dominic Raiola and left guard Rob Sims will start again, the group is built for the future.

Left tackle Riley Reiff, a first-round pick in 2012, is 25, and right guard Larry Warford, a third-round pick in 2013, is 23. Waddle, an undrafted free agent last year, is 23, as is third-round center Travis Swanson.

But this season, the play of Raiola and Sims largely will determine how strong the unit can be. Raiola is coming off his best of 13 seasons, and with Swanson on the team, he should be motivated. Raiola, however, is 35, and at some point, a decline will be natural.

Sims, meanwhile, played through an injury last season and is in a contract year, so he has plenty of motivation as well.

As for the youth, Warford looks like one of the top guards in the league based on his rookie season. Reiff was inconsistent last season, particularly as a pass blocker, but should be better.

Film review

Waddle’s rookie performance was impressive considering he didn’t play until Week 7 when Reiff left with an injury in the second quarter.

Waddle impressed from the start, pulling to the right side to create a nice hole for running back Reggie Bush.

His worst moments his first game came in the fourth quarter when he moved to right tackle after Hilliard left with an injury, giving up a quarterback pressure on back-to-back plays.

Waddle started the next eight games and was more consistent. He has great balance and uses his hands and long arms well to absorb initial contact when pass blocking.

Although he wasn’t overpowering in the run game, Waddle showed some ability. Against the Bears in Week 10, his downfield block led to a 39-yard run for Bush at the start of the third quarter. Bush also ran behind Waddle on back-to-back 11-yard gains in the fourth quarter.

Lions training camp position previews

Monday: Defensive backs

Tuesday: Linebackers

Wednesday: Defensive line

Today: Offensive line

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From left, Lions offensive linemen LaAdrian Waddle, Dominic Raiola and Larry Warford are returning members of a unit that gave up the second fewest sacks in the NFL last season. / Illustration by Tony Augusty / Detroit News