Defensive Coordinator: Teryl Austin
Austin achieved a true miracle with the Lions' defense, bringing about a radical change. This made him highly sought after in the head coaching market. However, he stayed in Detroit and now he will have to deal with the loss of the anchor of his defensive line, which was their greatest strength. His 4-3 defense will have a veteran like Haloti Ngata this year.
Defensive Star: Ziggy Ansah
One of the best defensive players of last year's season faces offensive lines without the support of Suh. It won't be easy for him to perform at the same level, but this defense will need him to shine.
Defensive Line
The big question mark for this team is whether the defensive line will reach a level close to the one it dominated in 2014. The defensive line was the team's strength, and now they will have to distribute the workload. Ngata is a player who has been demonstrating his level in the league for a long time. He is excellent against the run, capable of taking on double blocks, and getting to the QB. He is a great replacement for the loss of Suh, although it won't be the same. The other player to replace is Fairley, and they have added a player for the present (Walker) and another for the future (Wright). The former Auburn player is a DT who had a better year in 2013 than in 2014, but if they work on him and give him confidence, he can be a very interesting player. The sides of the line are two opposite poles. On one side, Ansah is improving by leaps and bounds and is becoming increasingly important. On the other side, Jones is not at the same level, and it remains to be seen what he can produce without the help of the two who have left.
Linebackers
The Lions have one of the most efficient LBs in the entire NFL. Levy had a very good year, capable of rushing the passer with speed and power that was highly dangerous for opposing O-lines. This WLB is one of the best LBs in coverage, is a very good reader of the QB, and knows the game perfectly. This year, he becomes the leader of the defense. Both Bynes and Tulloch offer more doubts. Both have benefited from the excellent DL they had, and although they are quality players, they will have to step up so that the transition this defense will undergo is as painless as possible. On the bench, two players are waiting who have the quality to try to make the jump to the starting lineup. Both Whitehead and Van Noy will compete for more snaps. Especially the latter, who left a bad taste in his mouth in his rookie year, as he has the quality to earn a spot in this defense.
Cornerbacks
Undoubtedly, the surprise of Detroit's defensive success in 2014 was the great performance of their secondary. It's logical that if you have one of the top three defensive lines in the league, everything behind it will benefit, but the quality leap was quite evident. Both Mathis and Slay were very solid in their work, avoiding dangerous situations when the opposing QB had time to throw. Despite the good performance of both, the team needed reinforcements, and in the draft, they chose an interesting player in Alex Carter, a cornerback with good size and very physical, capable of helping against the run. Diggs is another selection that will provide depth to this unit. In nickel, they have Lawson, but he is far from the level of the outside CBs.
Safeties
Just like with the cornerbacks, the safeties showed an excellent level in 2014, and just like in the previous position, the difference with the backups is quite wide. Glover Quin was splendid, and the acquisition of Ihedigbo in 2014 was perfect for him. In the Cover-2 that the Lions often play, both safeties demonstrate their coverage skills. However, they are not as reliable when they come down into the box to stop the run.
Special Teams
Jeremy Ross was acquired by the Lions to have a returner who could give them yards. After two years, Detroit realized that he is not what they were looking for. It was already evident in Green Bay that he didn't work in this aspect. However, their kicker and punter are up to par. Prater had a good 2014, with an 80% success rate on his kicks, and Martin (without doing anything extraordinary) also performed well. Finding a returner is a priority for this team.