The Detroit Lions had three different players start at right tackle last season. Jason Fox won the starting job in training camp, but he quickly got injured at the start of the regular season. This gave Corey Hilliard a chance to start, but more injuries eventually led to undrafted rookie LaAdrian Waddle stepping in as the starting right tackle. He performed so well that he made eight straight starts before sitting out the final game of the season with an injury of his own.
Given that he did so well last year, the thinking this offseason has been that Waddle will continue to be the Lions' starting right tackle, especially with Fox now in Miami. However, at least for right now, Hilliard is still getting a look for the starting right tackle job. ESPN's Michael Rothstein reports that both Waddle and Hilliard "have been spending time with the first group," indicating that Waddle's starting spot is not set in stone.
If this position battle were based simply on what happened in 2013, then Waddle would be a lock to continue to start at right tackle. Pro Football Focus gave him a +7.9 grade last season, whereas Hilliard received a -1.5 mark. (Fox, for what it's worth, got a -1.9 grade.) Waddle definitely had a few "rookie moments," but generally speaking, he was the better player in 2013.
Of course, it's important to remember that the Lions have a new coaching staff and a new offensive scheme, and Hilliard was in Indianapolis with Jim Caldwell for a couple seasons. That's not to say that Hilliard will win the job because of any of those factors, but the Lions are at least giving him a shot at taking back the starting spot at right tackle.