Ask Matt Patricia, the Lions’ new head coach, for his philosophy about building an NFL roster and he’ll start right about where his team is at the moment. He’ll start in the middle. “What I’ll tell you is this: When you build — and this is on both sides of the ball — you want to build from the ball out,” Patricia said this week at the NFL scouting combine. “So, starting in the middle and working out.” That’s probably worth remembering as the Lions and the rest of the league spend the weekend watching big men —really big men — try do all the little things right, whether in agility drills on the field at Lucas Oil Stadium during the day or individual interviews at the hotel across the street each night. The Lions have needs in the middle of their offensive and defensive lines. And while they’ll likely address some of those issues in free agency this month, they’re also keenly focused on interior linemen at the combine. The good news for Detroit is it appears there are plenty of talented ones from which they can choose. “This draft offers a lot of linemen that will be starters and good players,” said Duke Tobin, the Cincinnati Bengals’ director of player personnel. Likewise, NFL draft analyst Mike Mayock says he sees good depth at the guard and center positions, “and the interior defensive line — it is stacked early.” The offensive linemen took their turn for on-field drills Friday, with all eyes on Notre Dame guard Quenton Nelson, who figures to be a top-10 pick. Nelson opted not to run the 40-yard dash due to a hamstring pull, but there were other impressive performances.