4. Starting LB alongside Alex Anzalone
For better or worse, Alex Anzalone is locked in as one of the Lions' starting linebackers in base nickel. And yes, nickel (five defensive backs) is their base defense (75 percent of the time last year, fourth-highest rate in the league according to Sports Info Solutions). So those who have liked to say it can go ahead and park the "they'll start three linebackers" talk. The NFL is a passing league, with a lot of three-wide (or more) sets, and nickel is a primary defense to matchup with it.
So the battle is for who will start alongside Anzalone. Rookie first-round pick Jack Campbell is easy to anoint as the guy, but he is obviously not going to be guaranteed anything. And it's not as if Malcolm Rodriguez is some pushover stiff, after putting up 87 total tackles last year as a rookie. Derrick Barnes got first-team reps during OTAs, as Rodriguez dealt with a minor injury, and he shouldn't be forgotten in the battle for the starting job.
It's fair to assume there will be room for Campbell, Rodriguez and Barnes to make an impact on the Lions' defense this season. But there will be a natural pecking order, starting with who earns it in camp and stands out among his peers.