2015 Rank: 26
2014 Rank: 4
Fall: 22 spots

Only one year after having the league’s best run defense in a landslide, the Lions fielded the NFL’s 22nd-ranked run defense in 2015.

What happened? To start, Ndamukong Suh left for Miami in free agency, and his replacement, Haloti Ngata, wasn’t the same impact player he had been with the Baltimore Ravens.

To make matters worse, DeAndre Levy, who finished second in tackles to only Luke Kuechly in 2014, sustained a hip injury in training camp and went on to miss the entire season. Cornerback Rashean Mathis, who excelled in 2014, missed much of the season with a concussion, although Darius Slay and Quandre Diggs both stepped up and will return as starters next season.

Although he isn’t Suh, Ezekiel Ansah recorded 14.5 sacks and forced 4cfumbles after combining for 15.5 sacks in his first two NFL seasons.